Risk Analysis of Restrictive Factors for Fast-Track Knee Arthroplasty-A Retrospective Study of 1,224 Patients.

INTRODUCTION: With the implementation of a fast-track principle as an interdisciplinary and multimodal concept, an accelerated convalescence and reduction of postoperative complications and a reduction of hospital stay can be achieved. This has been shown not only to increase patient satisfaction but in reduction of hospital cost as well. However, the concept cannot be successfully implemented in all patients. Patients who require an extended length of stay (LOS) after surgery can profit from optimizations of postoperative care and rehabilitation as well. Therefore, early identification of such patients is desirable. This case control study aimed to identify patient characteristics and patient-independent factors that may affect fast-track programs and lead to extended length of stay in knee arthroplasty. MATERIALS AND METHODS: From October 2007 to May 2013, 1224 patients were treated at the University Hospital Halle (Saale) with a total knee arthroplasty (TKA). A maximum stay of seven days was defined as the target of the "fast-track arthroplasty" concept. There were 164 patients (13%) that did not reach this timeframe and were assigned to the case group (n=164). Each case group patient was compared to a patient with an inpatient stay of seven days or less who was operated on the same day and by the same surgeon. These patients formed the control group (n=164). In addition to causes for extended LOS, metadata (age, sex, body mass index [BMI]), chronic nicotine and alcohol abuse, American Society of Anesthesiology (ASA) score, blood transfusion necessity, and comorbidities were determined. The statistical analysis included two sample t-tests, a chi-square test, and logistic regression analyses. Additionally, 95% confidence intervals were calculated (p<0.05). RESULTS: Gender distribution in both groups showed no differences (case group: 40.2% male, 59.8% female vs. control group: 32.3% male, 67.7% female). The ø age in the case group was 69.6 ± 8.7 years, significantly higher than that of the control group with 66.5 ± 9.4 years (p=0.002). Another difference between the groups was seen in the need for red blood cell transfusion (case group 51.2%, control group 39.6%, p=0.03). The need for postoperative antibiotic therapy was associated with a 3.741-fold risk of prolonged hospital stay. ASA score and BMI were identical in both groups. For the patients with positive nicotine abuse, the regression analysis showed a 2.465-fold risk of prolonged length of stay. Alcohol abuse did not appear to play a role in length of stay in our patient cohort. For pre-existing conditions, patients from the case group were more likely to have a cardiac burden than those from the control group (p=0.03). The most common causes of prolonged LOS were elevated CRP followed by effusion and delayed wound healing. CONCLUSION: The study shows that especially patient age, the presence of cardiac secondary diseases, nicotine consumption, and patient-independent factors like blood loss could have a negative influence on convalescence. Despite constant cost reductions in the healthcare system, the concept of "fast track arthroplasty" should always be adapted to the specifics of each individual patient in view of increasing patient age or critically questioned already preoperatively.

Imaging Threshold for Assessment of the Correct Reduction in the Treatment of Unstable Syndesmotic Injuries - A Retrospective Analysis of 57 CT Scans.

INTRODUCTION: An incongruence of the distal tibiofibular joint (TFJ) after treatment of upper ankle joint injury represents a prearthrotic deformity and must be corrected. The objectives of this study were to analyze postoperative CT scans after surgical treatment of unstable syndesmotic injuries, and to determine the prevalence of syndesmotic malreduction and its contributing factors. The specific parameters of three-dimensional imaging for objective detection of malreduction should be identified as a helpful intraoperative imaging threshold. MATERIALS AND METHODS: Postoperative CT scans of 57 patients were analyzed by identifying cases requiring correction. Factors that influenced the reduction result (patient age, sex, fracture type and surgeon qualifications) were evaluated. The following CT measurements were determined: anterior (AD) and posterior tibiofibular distance (PD), TFJ width, anteroposterior fibular translation (APT), length and rotation of the fibula, position of the malleoli to the talar joint surface. A confidence interval of 95% was assumed (significance level p < 0.05). RESULTS: A very high proportion of the cases required revision (38.5%). Age (p=0.199), sex (p=0.752), body mass (p=0.722), and fracture type (p=0.266) had no significant influence on the reduction result. The risk of requiring correction was slightly lower for well-experienced trauma surgeons. The measurements revealed the following thresholds: AD: ø 3.2 mm (±2.2), PD: ø 5.1 mm (±2.2), TFJ: ø 3.4 mm (±1.4), APT: ø 7.9 mm (±3.5), and rotation: ø 10.7° (±6.8). The fibula was too long in 4 cases (7%) and too short in 8 cases (14%). There was a malleolar incongruence in 5 cases (8.7%). The analysis revealed a significant correlation between the ratio of the anterior and posterior tibiofibular distances and a need for correction. CONCLUSION: The ratio between the anterior and posterior tibiofibular distances in the axial sectional image is an aid for intraoperative assessment of the correct reduction in the TFJ.

Individual computer-assisted 3D planning for placement of auricular prosthesis anchors in combination with an implantable transcutaneous bone conduction hearing device in patients with aural atresia.

BACKGROUND: The simultaneous implantation of the Bonebridge (MED-EL, Innsbruck, Austria), a semi-implantable active transcutaneous bone conduction hearing device and anchors for auricular prostheses can be challenging as both implants contain magnets and compete for the narrow space in the designated implantation area. MATERIAL AND METHODS: A preoperative planning tool (virtual surgery) was used with individual 3D computer models of the skull and implants for finding optimal implant positions for both the floating mass transducer (FMT) and the anchors for the auricular prosthesis. The interaction between the magnetic prosthesis anchors and the FMT was measured by means of static magnetic forces. A retrospective data analysis was conducted to evaluate the surgical and audiological outcome. RESULTS: Between 2014 and 2021, a 3D planning of a simultaneous implantation of the Bonebridge with auricular prosthesis anchors was conducted on 6 ears of 5 patients (3 males, 2 females; age range 17-56 years). The individual preoperative planning was considered very useful for the optimal placement of bone anchors in combination with the Bonebridge. Audiological data showed a clear benefit for hearing 3 months and > 11 months after implantation. No adverse interactions between the magnetic prosthesis anchors and the FMT were observed. In two patients, revision surgery was carried out due to skin inflammation or wound healing problems. No long-term complications were observed 3-5 years after surgery. CONCLUSION: Preoperative 3D planning represents a clear benefit for the simultaneous audiological and esthetic rehabilitation using the Bonebridge and anchors for auricular prostheses.

[Individual computer-assisted 3D planning for placement of auricular prosthesis anchors in combination with an implantable transcutaneous bone conduction hearing device in patients with aural atresia. German version]. / Individuelle computergestützte 3D-Planung zur Platzierung von Epithesenankern in Kombination mit einem implantierbaren transkutanen Knochenleitungshörgerät bei Patienten mit Ohrfehlbildungen.

BACKGROUND: The simultaneous implantation of the Bonebridge (MED-EL, Innsbruck, Austria), a semi-implantable active transcutaneous bone conduction hearing device and anchors for auricular prostheses can be challenging as both implants contain magnets and compete for the narrow space in the designated implantation area. MATERIAL AND METHODS: A preoperative planning tool (virtual surgery) was used with individual 3D computer models of the skull and implants for finding optimal implant positions for both the floating mass transducer (FMT) and the anchors for the auricular prosthesis. The interaction between the magnetic prosthesis anchors and the FMT was measured by means of static magnetic forces. A retrospective data analysis was conducted to evaluate the surgical and audiological outcome. RESULTS: Between 2014 and 2021 a 3D planning of a simultaneous implantation of the Bonebridge with auricular prosthesis anchors was conducted on 6 ears of 5 patients (3 males, 2 females; age range 17-56 years). The individual preoperative planning was considered very useful for the optimal placement of bone anchors in combination with the Bonebridge. Audiological data showed a clear benefit for hearing 3 months and > 11 months after implantation. No adverse interactions between the magnetic prosthesis anchors and the FMT were observed. In two patients, revision surgery was carried out due to skin inflammation or wound healing problems. No long-term complications were observed 3-5 years after surgery. CONCLUSION: Preoperative 3D planning represents a clear benefit for the simultaneous audiological and esthetic rehabilitation using the Bonebridge and anchors for auricular prostheses.

Correction to: The High Flex Total Knee Arthroplasty-Higher Incidence of Aseptic Loosening and No Benefit in Comparison to Conventional Total Knee Arthroplasty: Minimum 16-Years Follow-Up Results.

[This corrects the article DOI: 10.1007/s43465-020-00276-3.].

Correction to: The High Flex Total Knee Arthroplasty-Higher Incidence of Aseptic Loosening and No Benefit in Comparison to Conventional Total Knee Arthroplasty: Minimum 16-Years Follow-Up Results.

[This corrects the article DOI: 10.1007/s43465-020-00276-3.].

The High Flex Total Knee Arthroplasty-Higher Incidence of Aseptic Loosening and No Benefit in Comparison to Conventional Total Knee Arthroplasty: Minimum 16-Years Follow-Up Results.

PURPOSE: This prospective randomized study compares the clinical and radiographic long-term results at least 16 years after total knee arthroplasty (TKA) between a mobile-bearing high flex and a fixed-bearing posterior-stabilized knee. METHODS: In 2000, we included 60 patients who underwent a TKA. Patients were divided into two groups. At the time of the follow-up after a minimum of 16 years (16.5 years ± 0.6), 16 patients had died for causes unrelated to the operation, 15 were lost to the follow-up. Five patients of the high flex group had a revision. The final evaluation included the hospital for special surgery score (HSS) and radiographs. Using the X-rays and the Knee Society Roentgenographic Evaluation and Scoring System, radiolucent lines and the maximal knee flexion were determined. RESULTS: No significant differences between the two groups were found. The mean HSS score of LPS group patients was 87.9 (± 10.6) points and that of the high flex group was 93.1 (± 7.4) points. Five patients of the high flex group had undergone a reoperation. One knee was revised for painful mid-flexion instability and the others for symptomatic aseptic loosening of the components. CONCLUSION: The long-term follow-up does not show any clear benefits and even a higher incidence of implant loosening using the mobile-bearing high-flex knee.

Long-term pre-clinical evaluation of an injectable chitosan nanocellulose hydrogel with encapsulated adipose-derived stem cells in an ovine model for IVD regeneration.

The potential therapeutic benefit of adipose-derived stem cells (ASCs) encapsulated in an injectable hydrogel for stimulating intervertebral disc (IVD) regeneration has been assessed by a number of translational and preclinical studies. However, previous work has been primarily limited to small animal models and short-term outcomes of only a few weeks. Long-term studies in representative large animal models are crucial for translation into clinical success, especially for permanent stabilization of major defects such as disc herniation. An injectable chitosan carboxymethyl cellulose hydrogel scaffold loaded with ASCs was evaluated regarding its intraoperative handling, crosslinking kinetics, cell viability, fully-crosslinked viscoelasticity, and long-term therapeutic effects in an ovine model. Three IVDs per animal were damaged in 10 sheep. Subcutaneous adipose tissue was the source for autologous ASCs. Six weeks after IVD damage, two of the damaged IVDs were treated via ASC-loaded hydrogel injection. After 12 months following the implantation, IVD disc height and histological and cellular changes were assessed. This system was reliable and easy to handle intraoperatively. Over 12 months, IVD height was stabilized and degeneration progression significantly mitigated compared to untreated, damaged IVDs. Here we show for the first time in a large animal model that an injectable chitosan carboxymethyl cellulose hydrogel system with encapsulated ASCs is able to affect long-term stabilization of an injured IVD and significantly decrease degeneration processes as compared to controls.

Risk analysis of restrictive factors for fast-track hip arthroplasty - a retrospective study of 1138 patients.

Fast track programs have been introduced to reduce perioperative complication rates and to quickly reintegrate the patient into everyday life. The aim of this retrospective case-control study was to identify patient characteristics and patient-independent factors that influence fast track programs in hip arthroplasty. A total of 1138 patients were examined. A hospital stay of more than seven days was used to define the case group. In addition to the causes for the longer hospitalisation, age, sex, BMI, chronic nicotine and alcohol abuse, ASA score, surgical duration, anaemia and blood transfusion as well as concomitant diseases were assessed. The statistical analysis included two-sample t-test, chi-square test and logistic regression analyses. An 95% confidence interval was calculated (p<0.05). 16.9% of patients could not leave the hospital on the seventh day. The main causes were delayed wound healing (69.4%), increased CRP (43.0%>100 mg/l), and internal complications (19.7%). At a mean of 69.2 ± 10.7 years, the age of the case group was significantly higher than that of the control group, which had a mean of 63.3 ± 10.3 years (p<0.001). Cardiac comorbidities (p<0.001), BMI (p=0.023), and alcohol consumption (p<0.001) increased the risk for longer hospitalisation. Significant patient-independent factors were duration of the surgery (p<0.001) and transfusion (p<0.001). Successful application of fast-track hip arthroplasty is possible for every patient. However, longer hospi- talisation and delayed discharge must be taken into account for patients with advanced age, cardiac comorbidities, alcohol consumption, and high BMI.

Secure corridor for infraacetabular screws in acetabular fracture fixation-a 3-D radiomorphometric analysis of 124 pelvic CT datasets.

BACKGROUND: Acetabular fracture surgery is directed toward anatomical reduction and stable fixation to allow for the early functional rehabilitation of an injured hip joint. Recent biomechanical investigations have shown the superiority of using an additional screw in the infraacetabular (IA) region, thereby transfixing the separated columns to strengthen the construct by closing the periacetabular fixation frame. However, the inter-individual existence and variance concerning secure IA screw corridors are poorly understood. METHODS: This computer-aided 3-D radiomorphometric study examined 124 CT Digital Imaging and Communications in Medicine (DICOM) datasets of intact human pelves (248 acetabula) to visualize the spatial IA corridors as the sum of all intraosseous screw positions. DICOM files were pre-processed using the Amira® 4.2 visualization software. Final corridor computation was accomplished using a custom-made software algorithm. The volumetric measurement data of each corridor were calculated for further statistical analyses. Correlations between the volumetric values and the biometric data were investigated. Furthermore, the influence of hip dysplasia on the IA corridor configuration was analyzed. RESULTS: The IA corridors consistently showed a double-cone shape with the isthmus located at the acetabular fovea. In 97% of male and 91% of female acetabula, a corridor for a 3.5-mm screw could be found. The number of IA corridors was significantly lower in females for screw diameters ≥ 4.5 mm. The mean 3.5-mm screw corridor volume was 16 cm3 in males and 9.2 cm3 in female pelves. Corridor volumes were significantly positively correlated with body height and weight and with the diameter of Köhler's teardrop on standard AP pelvic X-rays. No correlation was observed between hip dysplasia and the IA corridor extent. CONCLUSION: IA corridors are consistently smaller in females. However, 3.5-mm small fragment screws may still be used as the standard implant because sex-specific differences are significant only with screw diameters ≥ 4.5 mm. Congenital hip dysplasia does not affect secure IA screw insertion. The described method allows 3-D shape analyses with highly reliable results. The visualization of secure IA corridors may support the spatial awareness of surgeons. Volumetric data allow the reliable assessment of individual IA corridors using standard AP X-ray views, which aids preoperative planning.

Mastoid Dimensions in Children and Young Adults: Consequences for the Geometry of Transcutaneous Bone-Conduction Implants.

OBJECTIVES: Bone-conduction implants (BCI) are available for adults and children who are aged 5 years or more. Because a transcutaneous bone-conduction implant introduced in 2013 does not completely fit into all adult mastoids, we investigated mastoid dimensions and the possibility of fitting the implant in children. DESIGN: Computed tomography scans of 151 mastoids from 80 children and young adolescents from the age of 5 months to 20 years and 52 control mastoids from 33 adults were retrospectively analyzed. After three-dimensional reconstruction, mastoid volume was measured. The chances of fitting the Bonebridge or a novel BCI were determined as a function of age. Implant diameter and implantation depths were virtually varied to identify the most advantageous dimensions for reducing the minimum age for implantation. RESULTS: Mastoid volume increased to 13.8 ml in female and 16.4 ml in male adult mastoids at ages 18.9 years (male) and 19.0 years (female). Without compromising the middle fossa dura or the sinus and without lifts, the Bonebridge implant fit in 81% of male adult mastoids and 77% of the female adult mastoids. For children, the 50% chance of fitting a Bonebridge in the mastoids was reached at age 12 years; with a protrusion of 4 mm (4-mm lifts), this age was reduced to >6 years. The novel BCI fit in 100% of male and 94% of female adult mastoids. CONCLUSIONS: Casing diameter is the most limiting factor for Bonebridge implantation in children. A modified implant casing with a truncated cone and reduced diameter and volume would increase the number of hearing impaired children who can be rehabilitated with a Bonebridge implant. Radiological planning for Bonebridge implantation is necessary in all children.

A prospective randomized radiographic and dual-energy X-ray absorptiometric study of migration and bone remodeling after implantation of two modern short-stemmed femoral prostheses.

BACKGROUND: The aim of this prospective randomized study was to analyze migration and strain transmission of the Metha™ and Nanos™ femoral prostheses. MATERIALS AND METHODS: Between 1 January 2011 and 2 April 2013, 50 patients were randomized to receive short-stemmed femoral prostheses. Metha™ stems were implanted in 24 patients (12 female, 12 male; mean age 58.7 years; mean body mass index [BMI] 27.4) and Nanos™ stems in 26 patients (10 female, 16 male; mean age 59.7 years; mean BMI 27.1). Longitudinal stem migration, varus-valgus alignment, changes of center of rotation (COR), femoral offset and caput-collum-diaphyseal angle, leg length discrepancy, periprosthetic radiolucent lines incidence, and dual-energy X-ray absorptiometry (DEXA) scans were analysed after an average of 98 and 381 days. RESULTS: There was no significant change of varus-valgus alignment or clinically relevant migration of the Metha™ or Nanos™ prostheses during postoperative follow-up. After 12.3 months, the DEXA scans showed small but significant differences of bone mineral density in Gruen zones 1 (minus ~8 %) and 6 (plus ~9 %) for the Metha™ and in Gruen zone 1 (minus ~14 %) for the Nanos™ (paired t test). Visual analog scale (VAS) and Harris Hip Score (HHS) improved significantly for both implants (Nanos™/Metha™ 12.3 months postoperatively HSS 96.5/96.2; VAS 0.7/0.8, respectively). COR or offset did not change significantly after surgery. CONCLUSIONS: Neither implant showed signs of impaired osseointegration. DEXA demonstrated proximally located load transfer with only moderate proximal stress shielding. LEVEL OF EVIDENCE: II.

Three-dimensional virtual simulation and evaluation of the femoroacetabular impingement based on "black bone" MRA.

INTRODUCTION: Femoroacetabular impingement (FAI) is a recognised cause of secondary osteoarthritis of the hip. Several imaging methods have been used to analyse the pathologic signs. Because of the lack of precise pre- and intraoperative overview and the difficulty locating osseous pathologies, arthroscopic and minimal invasive treatment is still challenging, even for trained surgeons. This paper describes a procedure that is based on magnetic resonance arthrography (MRA) and is used to virtually verify the range of motion (ROM) of the hip. It enables the evaluation of FAI and the preoperative simulation of adequate surgical manoeuvres. METHODS: Each MRI was completed on a 3.0 T system using a flexible transmit/receive surface body coil with the patient in the supine position. An axial three-dimensional (3D) gradient-echo (VIBE, volume interpolated breathhold examination) sequence was performed. For the generation of 3D bone models, semiautomatic segmentation of the MRA data was accomplished using Amira(®) visualisation software version 5.2. The self-developed software "HipProject", written in C++, computes the maximal ROM of the hip. The virtual colliding regions were visualised for verification and simulation of osseous trimming. RESULTS: In addition, for necessary information about damage to the cartilage and labrum, "black bone" MRA was used to generate extremely precise 3D reconstructions of the hip joint to automatically calculate the preoperative osseous ROM. Furthermore, the acetabular and femoral locations of the impingement zone were individually visualised and quantified. CONCLUSIONS: The described procedure is a useful tool for the preoperative investigation of impinging hips. It enables appropriate planning of required surgical interventions.

Functional results after Bonebridge implantation in adults and children with conductive and mixed hearing loss.

In patients with conductive hearing loss caused by middle ear disorders or atresia of the ear canal, a Bonebridge implantation can improve hearing by providing vibratory input to the temporal bone. The expected results are improved puretone thresholds and speech recognition. In the European Union, approval of the Bonebridge implantation was recently extended to children. We evaluated the functional outcome of a Bonebridge implantation for eight adults and three children. We found significant improvement in the puretone thresholds, with improvement in the air-bone gap. Speech recognition after surgery was significantly higher than in the best-aided situation before surgery. The Bonebridge significantly improved speech recognition in noisy environments and sound localization. In situations relevant to daily life, hearing deficits were nearly completely restored with the Bonebridge implantation in both adults and children.

The influence of injecting an epidural contrast agent into the sacral canal on the fluoroscopic visibility of bony landmarks for sacroiliac screw fixation: a feasibility study.

OBJECT: In sacroiliac screw fixation of unstable pelvic injuries in geriatric patients, poor bone quality often obscures important bony landmarks in fluoroscopic images. The authors analyzed the feasibility of injecting a transhiatal contrast agent (CA) into the sacral canal to improve fluoroscopic visualization in the sacral epidural space. METHODS: Eight fresh cadaveric whole-body specimens from human donors whose mean age at the time of death was 78 years (range 69-87 years) were used. First, to identify bony landmarks without CA enhancement, the authors acquired fluoroscopy images of the native sacral canal, using lateral, inlet, and outlet projections. Through puncture of the sacral hiatus, 8-10 ml of CA was injected into the epidural space. Fluoroscopy images were then acquired in the standard pelvic views to identify the bony landmarks. To assess the effect of the CA enhancement, visibility of the landmarks was assessed before and after CA injection. Each identified landmark was scored as 1, and summative landmark scores of up to 10 were determined for each specimen. RESULTS: The cadaveric specimens were representative of bone structures in the geriatric population. In all specimens, epidural CA injection enhanced the fluoroscopic visualization of the sacral canal and of the S-1 foramina. The enhancement increased the total bony landmark score from 5.9 (range 4-8) without CA injection to 8.1 (range 6-10) after CA injection. Considering only intrasacral landmarks, the score was increased from 1.5 to 3. CONCLUSIONS: Injection of a transhiatal epidural CA improves fluoroscopic imaging of the sacral canal and of the neural foramina. Hence, this technique could be applied to help the surgeon identify anatomical landmarks during sacroiliac screw fixation in geriatric patients.

Anatomical conditions of the posterior pelvic ring regarding bisegmental transverse sacroiliac screw fixation: a 3D morphometric study of 125 pelvic CT datasets.

INTRODUCTION: Sacroiliac (SI) screws are used for osteosynthesis in unstable posterior pelvic ring injuries. In the cases of "sacral dysplasia", in which the elevated upper sacrum does not allow a secure SI screw insertion into the S1 level, the S2 segment must be used to achieve stable fixation. The bone quality of the S2 segment is thinner compared to that of the S1 vertebra and may cause biomechanical weakness. An additional SI screw insertion into the S3 level may improve stability. With respect to the anatomical conditions of the posterior pelvic ring, there have been no anatomical investigations to date regarding SI screw placement into the third sacral segment. MATERIALS AND METHODS: CT raw datasets from 125 patients (ø59 years, ø172 cm, ø76 kg) were post-processed using Amira 5.2 software to generate 3D pelvic models. A program code implemented in C++ computed a transverse bone corridor for the first, second and third sacral segments for a typical SI screw diameter of 7.3 mm. Volume, sagittal cross-section, iliac entrance area and length of the determined screw corridors were measured. A confidence interval of 95 % was assumed (p < 0.05). RESULTS: The fully automatic computation revealed a possible transverse insertion for one 7.3-mm screw in the third sacral segment in 30 cases (24 %). The rate (60 %) of feasible S3 screw placements in the cases of sacral dysplasia (n = 25) is significantly higher compared to that (15 %) of "normal" sacra (n = 100). With regard to the existence of transverse iliosacroiliac corridors as a function of sacral position in between the adjacent iliac bone bilaterally, a new classification of three different shape conditions can be made: caudad, intermediate minor, intermediate major, and cephalad sacrum. Gender, age, body height and body weight had no statistically significant influence on either possible screw insertion or on the calculated data of the corridors (p > 0.05). CONCLUSION: SI screw insertion into the third sacral level deserves discussion in the cases of sacral dysplasia. Biomechanical and practical utility must be verified.

Individual computer-assisted 3D planning for surgical placement of a new bone conduction hearing device.

OBJECTIVE: To evaluate the benefit of a preoperative three-dimensional (3D) planning tool for surgically placing the bone conduction floating mass transducer (BC-FMT) of the Bonebridge (BB) bone conduction implant. PATIENTS: Adult patients (n = 5) and one pediatric patient (n = 1) with conductive or mixed hearing loss caused by chronic ear disease, malformation, or single-sided deafness. INTERVENTION(S): Development of a preoperative planning tool that allowed free adjustment of the implant in an individual 3D model of the skull to evaluate completely fitting the BC-FMT into a bony bed and to identify an optimal implant position. Implantation of the BB with mastoid or retrosigmoid placement after individual preoperative planning and "virtual surgery". MAIN OUTCOME MEASURES: Feasibility of the preoperative 3D planning process, transfer into the intraoperative situation, and audiologic results after BB implantation. RESULTS: Individual preoperative planning was considered beneficial especially in cases of small mastoid bone volume, for example, because of previous canal wall down mastoidectomies, and in the case with malformation. CONCLUSION: For optimal placement of the BC-FMT of the BB, preoperative 3D planning is recommended especially in primarily small poorly pneumatized mastoids, hypoplastic mastoids in malformations, reduced bone volume after canal wall down mastoidectomy, or the small mastoids in children. Effort should be made to reduce segmentation and surgical planning time by means of automation.

High flex total knee arthroplasty--a prospective, randomized study with results after 10 years.

This prospective randomized study compares the long term results between total knee arthroplasty with a mobile bearing high flex and a fixed bearing posterior stabilized knee (LPS) in 39 patients. The Hospital for Special Surgery score (HSS) was calculated and radiographs in AP and lateral view were analyzed after a minimum follow-up of 10 years. No significant differences between the two groups were found. The mean HSS-score was 90.67 (+/- 5.75) for LPS group patients and 90.83 (+/- 8.57) points for the high flex group patients. Three patients in the high flex group had undergone a reoperation on their knee. One knee was revised for painful mid-flexion instability and the others for symptomatic aseptic loosening of the tibial prosthesis. Based on these and other findings, the use of a high flex knee system may be seriously re-considered. Further studies are required to evaluate possible long-term adverse effects of high flex knee systems.

CT-based 3-D visualisation of secure bone corridors and optimal trajectories for sacroiliac screws.

Sacroiliac screw (SI) fixation represents the only minimally invasive method to stabilise unstable injuries of the posterior pelvic ring. However, it is technically demanding. The narrow sacral proportions and a high inter-individual shape variability places adjacent neurovascular structures at potential risk. In this study a CT-based virtual analysis of the iliosacral anatomy in the human pelvis was performed to visualise and analyse 3-D bone corridors for the safe placement of SI-screws in the first sacral segment. Computer-aided calculation of 3-D transverse and general SI-corridors as a sum of all inner-bony 7.3-mm screw positions was done with custom-made software algorithms based on CT-scans of intact human pelvises. Radiomorphometric analysis of 11 CT-DICOM datasets using the software Amira 4.2. Optimal screw tracks allowing the greatest safety distance to the cortex were computed. Corridor geometry and optimal tracks were visualised; measurement data were calculated. A transverse corridor existed in 10 pelvises. In one dysmorphic pelvis, the pedicular height at the level of the 1st neural foramina came below the critical distance of 7.3mm defined by the outer screw diameter. The mean corridor volume was 45.2 cm3, with a length of 14.9cm. The oval cross-section measured 2.8 cm2. The diameter of the optimal screw pathway with the greatest safety distance was 14.2mm. A double cone-shaped general corridor for screw penetration up to the centre of the S1-body was calculated bilaterally for every pelvis. The mean volume was 120.6 cm3 for the left side and 115.8 cm3 for the right side. The iliac entry area measured 49.1 versus 46.0 cm2. Optimal screw tracks were calculated in terms of projected inlet and outlet angles. Multiple optimal screw positions existed for each pelvis. The described method allows an automated 3-D analysis with regard to secure SI-screw corridors even with a high number of CT-datasets. Corridor visualisation and calculation of optimal screw tracks trains the visual thinking of the surgeon and can improve pre-operative planning. Prospectively, the introduced method can be implemented in computer-assisted surgery applications involving pelvic trauma.

Quality of life and radiological outcome after cervical cage fusion and cervical disc arthroplasty.

In this retrospective comparative study, 42 patients with single-level cervical radiculopathy were operated upon, either with Shell cage fusion (23 patients) or with Prestige cervical disc arthroplasty (19 patients). The mean follow-up (FU) was 17.5 months (range: 5.6-42.1 months). Both treatments significantly improved all clinical parameters (VAS, ODI, SF36) (p < 0.001), without statistically relevant differences between the two groups. From a radiological viewpoint there was an obvious but statistically non-significant increase in the segmental height for both treatment groups. Segmental angle also increased in both groups, and the increase was significant (p < 0.05). As expected, range of motion (ROM) decreased significantly (p < 0.05) in the fusion group, while it was preserved in the arthroplasty group. Significantly more (p < 0.05) adjacent level degeneration class 1 to 4 was evident in the fusion group (8/23 or 34.8%) than in the arthroplasty group (3/19 or 15.8%). Two fusion patients (2/23 or 8.7%) developed painful clinical adjacent level disease requiring arthroplasty. The major conclusion was that significant adjacent level degenerative changes occurred in the cage group. Retained motion at the operative site seems to decrease the incidence of adjacent level degeneration. Implant subsidence was recorded at FU in 8 out of 42 patients (19%). It occurred significantly (p < 0.05) more often in the fusion group (6/23 or 26.1%) than in the arthroplasty group (2/19 or 10.5%), but it did not cause clinical symptoms. As in other studies, there is no explanation as to why better radiological results did not translate into better clinical outcomes within the time limits of the study.