Migration Of Prosthesis Research Articles

High prevalence of heterotopic ossification after cervical disc arthroplasty: outcome and intraoperative findings following explantation of 22 cervical disc prostheses

Cervical disc arthroplasty (CDA) has been increasingly used for the treatment of cervical disc herniations. However, the impact of CDA on adjacent-segment degeneration and the degree of heterotopic ossification (HO) of the treated segment remain a subject of controversy. Due to a product failure of the Galileo-type disc prosthesis, 22 of these devices were explanted. The radiological and clinical course in each case was investigated in detail with an emphasis on the incidence of HO and facet joint degeneration 18 months following the operation. Intraoperative findings regarding ossification and implant fixation were documented. Thus, the authors were able to describe the true rate of adjacent-segment degeneration and HO following CDA and the clinical relevance thereof. In all 22 patients, functional radiographic imaging was performed prior to surgery, 3 and 12 months after surgery, and prior to disc prosthesis explantation. At all time points, the range of motion (ROM) in the operated and adjacent segments was determined. A motion index was calculated using the preoperative and all postoperative ROMs (preoperative ROM/postoperative ROM). Computed tomography was used preoperatively to measure the height of the index segment, extent of HO, and the degree of the progression of facet arthrosis, and was used postoperatively prior to prosthesis explantation. Patients completed clinical questionnaires that included a visual analog scale and the Neck Disability Index. The motion index of the index segment declined gradually from 1.4 at 3 months postoperative to 1.2 prior to explantation, while the motion index of the adjacent upper segment increased from 0.9 to 1.3. The mean ROM of the index segment was 10.4° ± 6.7°, and fusion was observed in 2 (9%) of the 22 patients. Prosthesis migration was present in 3 patients (13.6%). Severe HO (Grades 3 and 4) was present in 17.4%. Computed tomography showed a significant increase of segmental height of the index segment (1.6 ± 1.1 mm, p = 0.035), and a significant increase of left-sided lateral osteophytes (1.7 ± 2.1 mm, p = 0.009). The incidence of severe osteophyte formation (> 2 mm) occurred in 40%. Intraoperative findings reflected the results from CT, with primary lateral proliferation of osteophytes found in approximately 25% of patients. The mean visual analog scale scores were 3.8 ± 2.7 (neck) and 2.4 ± 2.5 (arms), and the mean Neck Disability Index score was 30 ± 22. No correlation was found between radiological and clinical parameters. In this study, a higher incidence of HO after CDA could be demonstrated using CT, compared with studies using fluoroscopy only. However, patient selection and/or the operative technique might have contributed to the high prevalence of osteophyte formation. Thus, the exact indication for CDA has to be reconsidered. Because implant migration was detected, using fixation in the present CDA model appears suboptimal.

Sizing the aortic annulus.

Transcatheter aortic valve implantation (TAVI) is a valuable alternative for aortic valve replacement in selected high-risk candidates. Accurate preoperative assessment of the aortic annular dimensions is crucial for the success of TAVI, since choice of an incorrectly sized prosthesis may result in catastrophic complications. These complications include annular rupture and coronary arterial obstruction, if the prosthesis is too big, or prosthesis migration and severe paravalvular leakage, if the prosthesis is too small. According to current recommendations, the choice of prosthesis size is based on transoesophageal echocardiography (TEE) measurements. However, TEE results are dependent on operator experience. Moreover, recent research has shown that TEE can significantly underestimate annular dimensional measurements. Alternative sizing methods based on Multidetector Computed Tomography (MDCT) or manometry during balloon aortic valvuloplasty have therefore been developed. We present a brief overview of the imaging modalities available for preoperative assessment of annular size and discuss their potential advantages and limitations.

A survivor of late prosthesis migration and rotation following percutaneous transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI) has emerged as a viable alternative endovascular technique in selected patients with severe aortic stenosis, who are either inoperable or at high risk for surgical aortic valve replacement. We report a case of delayed displacement and rotation of an aortic bioprosthesis, 43 days after successful TAVI via the transfemoral approach, with the patient surviving the subsequent open heart surgery required for device retrieval.

A Case of Acute Prosthesis Migration after Femoral Head Replacement due to Osteomalacia by FGF23-Induced Tumor

Fibroblast growth factor 23 (FGF23) was recently identified as an important factor involved in the development of hypophosphatemic rickets and osteomalacia. We experienced a rare case of acute prosthesis migration after hemihip arthroplasty due to FGF23-induced tumor. The patient underwent femoral head replacement because of femoral neck fracture, but prosthesis migration was occurred at 1 week after operation. The patient took various examinations, and FGF23-induced tumor was found in his right wrist. The tumor was resected, and he underwent total hip arthroplasty 8 month later. Finally, he was able to obtain free gait without pain.

Comment on: Markmiller M, Weiss T, Kreuz P, Rüter A, Konrad G. Partial weightbearing is not necessary after cementless total hip arthroplasty. Int Orthop. 2011 Aug;35(8):1139-43

We read with interest the article by Markmiller et al. [1] that discussed an important issue regarding time of weight bearing after cementless total hip arthroplasty. Although we agree with the conclusion drawn from their observations, we ask clarification on several points in their methods. The authors mention that they used radiographs to measure subsidence and migration postoperatively, but as radiographs are prone to errors due to patient positioning and radiograph centring [2], were any specific steps taken to ensure minimal errors, and how was radiograph uniformity ensured during follow-up? Furthermore, all measurements were done manually by an orthopaedic surgeon. Were these measurements made on radiographs or digital images? Was any specific software used for making these measurements? There are several software packages available, such as Ein-Bild-Roentgen-Analyse (EBRA) that have been validated previously [2, 3]. These are available free and are easy to use. Although Roentgen stereophotogrammetric analysis (RSA) provides the best method for making these measurements, its availability might be an issue at several centres. We would further like to know the impact of femoral anatomy (according to Dorr types) in choice of patients for cementless femoral stem and any possible difference in prosthesis migration amongst different femoral canal morphologies [4]. In our opinion, although this study makes important and valid inferences regarding the relation between weight bearing and subsidence or migration in THR, better methods could have been used to provide firmer conclusions.

Prise en charge des sténoses de l’anastomose gastrojéjunale après by-pass gastrique: plaidoyer pour une « vraie » prise en charge multidisciplinaire

We report herein the case of Mrs. C. who presented a stenosis of the gastrojejunal anastomosis after gastric bypass. Endoscopic maneuvers had to be repeated because of recurrent stenosis. They have finally concluded by an acute small bowel obstruction by a migration of prostheses and their incaceration in the jejuno-jejunal anastomosis. We believe that a multidisciplinary discussion might sometimes prevent such complications.

Is there an increased stem migration or compromised osteointegration of the Mayo™ short-stemmed prosthesis following cerclage wiring of an intrasurgical periprosthetic fracture?

Short-stemmed prostheses are increasingly regarded as implants of first choice in primary THA. As a result of the press-fit fixation in the femoral metaphysis, the occurrence of intraoperative fractures were reported. The aim of this study was to analyze the postoperative results of the Mayo short-stem prosthesis following treatment of an intrasurgical femur fracture with cerclage wiring. From 1999 to 2005, in 38 patients (18 females, 20 males; mean age 56 years; mean BMI = 27) with the diagnosis of coxarthrosis in whom a Mayo short-stemmed prosthesis has been implanted, an intraoperative fracture was observed. The fractures were treated with cerclage wiring (1 cerclage, n = 32; 2 cerclages, n = 5; 3 cerclages, n = 1). Postoperatively, all patients were prescribed mobilization without weight-bearing (floor contact) on the treated leg for 6 weeks. Using the Wristing software, longitudinal stem migration and varus-valgus femoral stem alignment were examined digitally in anteroposterior X-rays taken immediately after surgery, after 6 weeks and on average after 5.7 years (Zeh et al., Z Orthop Unfall 149:200-205, 2011). Additionally, the incidence of periprosthetic radiolucent lines was captured in the anteroposterior X-rays and assigned to the Gruen zones. Additionally, a DEXA scan was performed. The X-rays of a matched control group after the implantation of a Mayo prosthesis without femur fracture were analyzed by the same method. There was no significant migration of the Mayo prosthesis in the study or control groups during postoperative follow-up (t test, P > 0.05). The cerclage group compared with the control group showed a statistically significant valgus tilt of 1.5° on average during the follow-up, which is regarded to be clinically not relevant. The frequency of occurrence of radiolucent lines was not statistically different (chi-square test, χ = 0.42, P = 0.51). DEXA scans showed no differences of the bone mineral density in the Gruen zones compared with a historical control group. After wiring of an intrasurgical fracture, no disadvantage could be proven for Mayo prosthesis regarding stem migration and varus-valgus alignment. Furthermore, due to the absence of differences in the occurrence of radiolucent lines and the same results in the DEXA scan, an unimpaired osseointegration is assumed.

Failure of cervical arthroplasty in a patient with adjacent segment disease associated with Klippel-Feil syndrome

Cervical arthroplasty may be justified in patients with Klippel-Feil syndrome (KFS) in order to preserve cervical motion. The aim of this paper is to report an arthroplasty failure in a patient with KFS. A 36-year-old woman with KFS underwent two-level arthroplasty for adjacent segment disc degeneration. Anterior migration of the cranial prosthesis was encountered 5 months postoperatively and was successfully revised with anterior cervical fusion. Cervical arthroplasty in an extensively stiff and fused neck is challenging and may lead to catastrophic failure. Although motion preservation is desirable in KFS, the special biomechanical features may hinder arthroplasty. Fusion or hybrid constructs may represent more reasonable options, especially when multiple fused segments are present.

Mittelfristige Ergebnisse der Mayo™-Kurzschaftprothese bei Hüftkopfnekrose

Short-stemmed prostheses are increasingly regarded as implants of first choice in coxarthrosis, especially in young patients. Despite promising short-term results, long-term follow-up studies are still lacking. Short-stemmed femoral implants are characterised by a metaphyseal osseointegration and strain distribution. Therefore a reduced stress shielding of the proximal femur is hypothesized and in some studies already proven. There is histological evidence that osteonecrosis (ON) of the femoral head may involve not only the intracapital region but also the femoral neck and metaphyseal area. This could lead to a higher rate of aseptic loosening of short-stemmed implants. The aim of this retrospective study was to analyze the midterm results of the Mayo™ short-stem prosthesis after ON with particular attention on osseointegration. From 2002-2004, in 21 patients (2 females, 19 males; mean age 45 years; mean BMI = 27) with secondary coxarthrosis after ON implantation of 26 Mayo™ Conservative Hips was performed. Postoperatively, all patients were mobilised with full weight-bearing. Using the specially developed Wristing® software, longitudinal stem migration and varus-valgus femoral stem alignment were examined digitally in anteroposterior X-rays taken immediately after surgery and in standing AP radiographs after 8.2 months and on average after 7.9 years (16 patients). The incidence of periprosthetic radiolucent lines was captured in the anteroposterior X-rays and assigned to the Gruen zones and a DEXA scan was performed. The X-rays of a matched control group with implantation of a Mayo™ short-stem prosthesis in primary coxarthrosis were analyzed by the same method. In all patients the Harris hip score (HHS) was obtained pre- and postoperatively. There was no significant migration or valgus tilt of the Mayo™ prosthesis in the study and control groups during postoperative follow-up (paired t-test, p = 0.13 and 0.69, respectively). In six of 26 Mayo™-Stems 12 radiolucent lines (RL) of the Mayo™ prosthesis were observed. The control group showed at ten of 30 Mayo™ stems 17 radiolucent lines. The difference between the groups was not statistically different (chi-square test for the total number of RL: χ² = 0.001, p = 1.0 and χ² = 0.06, p = 0.79 for the number of Mayo™ stems with RL). The DEXA scan showed a slightly higher bone mineral density (BMD) in Gruen zones 3 and 5 compared with a control group: study group. In the study group the postoperative HHS was 93.5 (SD 5.6) compared to 94.2 (SD 6.9) in the control group (t-test, p = 0.63). In the mid-term course no increased migration or tilt could be proven for Mayo™ short-stem THA in patients with osteonecrosis of the femoral head. Due to the absence of differences in the occurrence of radiolucent lines and the same results in the DEXA scan an unimpaired osseointegration of the Mayo™ stem is assumed. Therefore it is concluded that the Mayo™ Conservative Hip can be regarded as an alternative for operative treatment of ON of the femoral head.

Novel use of an air‐filled breast prosthesis to allow radiotherapy to recurrent colonic cancer

The authors present the novel and successful use of an air-filled breast prosthesis for extra pelvic exclusion of small bowel to facilitate adjuvant radiotherapy following resection of recurrent adenocarcinoma of the ascending bowel. The therapeutic use of radiotherapy in colon cancer can cause acute or chronic radiation enteropathy. Mobile small bowel can be sequestered in 'dead space' or by adhesions exposing it to adjuvant radiotherapy. A variety of pelvic partitioning methods have been described to exclude bowel from radiation fields using both native and prosthetic materials. In this case a 68 year old presented with ascending colon adenocarcinoma invading the peritoneum and underwent en bloc peritoneal resection. Thirty-seven months later surveillance CT identified a local recurrence. Subsequent resection resulted in a large iliacus muscle defect which would sequester small bowel loops thus exposing the patient to radiation enteropathy. The lateral position of the defect precluded the use of traditional pelvic partitioning methods which would be unlikely to remain in place long enough to allow radiotherapy. A lightweight air-filled breast prosthesis (Allergan 133 FV 750 cms) secured in place with an omentoplasty was used to fill the defect. Following well tolerated radiotherapy the prosthesis was deflated under ultrasound guidance and removed via a 7-cm transverse incision above the right iliac crest. The patient is disease free 18 months later with no evidence of treatment related morbidity. The use of a malleable air-filled prosthesis for pelvic partitioning allows specific tailoring of the prosthesis size and shape for individual patient defects. It is also lightweight enough to be secured in place using an omentoplasty to prevent movement related prosthesis migration. In the absence of adequate omentum a mesh sling may be considered to allow fixation. In this case the anatomy of the prosthesis position allowed for its removal without the need for repeat laparotomy. Pre-operative deflation of the air-filled prosthesis under ultrasound guidance also reduces the size of the incision required for removal. This technique may be valuable to prevent collateral small bowel irradiation following resection of renal or retroperitoneal malignancy.

Measuring Aortic Valve Annulus Size for Transcatheter Aortic Valve Implantation – 2D or 3D Imaging Techniques?

To date, more than 20,000 patients with severe symptomatic aortic valve stenosis and high-risk or contraindication to conventional surgery have been successfully treated with transcatheter aortic valve implantation (TAVI). The results of the multicentre randomised Placement of aortic transcatheter valve trial (PARTNER)7 have shown the superior long-term survival of patients who received a transcatheter aortic valve compared to patients who were medically treated. In order to optimise the procedural success rate and minimise the number of complications, patient selection and procedural strategy planning are crucial. Selection of prosthesis size is one of the key steps in this pre-procedural evaluation. Accurate measurement of the aortic valve annulus is pivotal to select the most appropriate prosthesis size and avoid complications such as prosthesis migration, paravalvular aortic regurgitation or aortic annulus rupture. Currently, the reference method to measure the aortic valve annulus dimension is still debated. While 2D echocardiography remains as the imaging modality of first choice to measure the aortic valve annulus, 3D imaging techniques have provided important information on the shape, geometry and spatial relationships of this structure. The present review provides an overview of the different imaging techniques to measure the aortic valve annulus and the inherent clinical implications of each technique.

A novel 14F endograft for abdominal aortic aneurysm: First in man

This study evaluated the feasibility of percutaneous endovascular treatment of infra-renal abdominal aortic aneurysm (AAA) using the novel low profile modular Tripelay system (Tripelay, France). Endovascular aortic aneurysm treatment (EVAR) has become more widely used as early mortality has been significantly reduced. Also, percutaneous access has become possible with the introduction of vascular closure devices and with the initial reduction in size of delivery catheters. However, percutaneous access is not commonly used and anatomical considerations, such as access vessel size and tortuousities, preclude a number of patients from being efficiently treated with EVAR. The novel Tripelay system enables two semicircular preshaped self-expandable stentgrafts to be positioned side by side on the aneurysm neck extending into the iliac arteries. Each stentgraft being smaller than the target vessel diameter, the delivery catheter is reduced in size (14F) and accommodates with smaller and more tortuous access vessels than conventional devices. This device was used to treat a 57-year-old male patient with significant comorbidities (previous coronary artery bypass grafting (CABG) and abdominal surgeries, smoking, hypertension, obesity, hyperlipidemia). Percutaneous access was made on both femoral arteries. The device was inserted, positioned, and deployed as planned. Iliac extensions were used bilaterally. The EVAR procedure was performed successfully, and the patient was discharged on day 6. Follow-up computed tomography scans at 1, 6, and 12 months revealed perfect exclusion of the aneurysm sac, patent stentgraft, and vessels, and no prosthesis migration, endoleaks or stent fracture were observed. The patient remained asymptomatic and reported no adverse events during that period. The Tripelay system seemed as an effective and user friendly tool for treatment of AAAs. Of course, this procedure still needs further clinical evaluation with more cases and longer follow-up to confirm long-term efficacy and safety of this device.

Radiological evaluation of allograft reconstruction in acetabulum with Ganz reinforcement ring in revision total hip replacement

BackgroundIn revision total hip replacement (THR), cages and rings are commonly used for the reconstruction of bone defects that are due to mechanical loosening of the acetabular cup and migration of the femoral head prosthesis. The purpose of this study was to evaluate the radiological results of the use of Ganz reinforcement rings with bone allografts in acetabular revision THR. MethodsWe reviewed 30 hips of 28 patients who underwent allograft reconstruction of the acetabulum with a Ganz reinforcement ring in revision THR. The average postoperative follow-up period was 8 years. The position of the acetabular socket was measured on anteroposterior radiographs. Loosening of the acetabular component was defined as a change in the cranial or central direction of the cup or a change in the cup inclination angle at the time of last follow-up. In cases of segmental bone defects in weight-bearing areas, we used two or three strut screws prior to incorporation of the Ganz reinforcement ring to act as struts for the ring. Kaplan-Meier survivorship analysis was performed. The end point was revision surgery done because of defined loosening of the acetabular component at the time of the last follow-up. ResultsAll five acetabular components (16.7%) defined as showing aseptic loosening were type D defects (cranio-central defects), but no patient needed revision surgery during the follow-up period. Nine revision surgeries with strut screws for type D acetabular bone defects were performed. The calculated Kaplan-Meier survival rate at 5 years was 96.0%, and the rate at 10 years was 80.2%, using defined loosening of the acetabular component as the end point. ConclusionsAllograft reconstruction of the acetabulum with a Ganz reinforcement ring is a useful technique for revision THR. Occasionally, a special technique (the strut screw technique) was required for the reconstruction of type D bone defects.

A quantitative method for determining medial migration of the humeral head after shoulder arthroplasty: preliminary results in assessing glenoid wear at a minimum of two years after hemiarthroplasty with concentric glenoid reaming

Glenoid erosion and medial migration of the humeral head prosthesis have been observed after most types of shoulder arthroplasty. A method of measuring the change in humeral head position with time after shoulder prosthetic arthroplasty was applied it to 14 shoulders that underwent humeral hemiarthroplasty with concentric glenoid reaming. We hypothesized that the measurement technique would be reproducible and that the rate of wear would be small in the series of shoulders studied. Standardized anteroposterior and axillary radiographs were obtained after surgery. Two examiners measured the position of the humeral head center in relation to scapular reference coordinates for the anteroposterior and axillary projections and plotted these values against time after surgery. The change in position was characterized as the slope of this plot. Shoulders were included if there were at least 3 sets of postoperative films, the last being at least 2 years after surgery. The slopes measured by the 2 examiners agreed within 0.5 mm/y for the anteroposterior and the axillary projections. For the series of shoulder arthroplasties, the rate of movement of the head center toward the scapula was less than 0.4 mm/y for either examiner in either projection. Medial migration is a concern after any type of shoulder arthroplasty, whether a hemiarthroplasty, a biological interpositional arthroplasty, or a total shoulder arthroplasty. Quantifying the rate of medial migration over time after shoulder arthroplasty is an important element of clinical follow-up. This is an inexpensive, practical, and reproducible method that can be used to determine the rate of medial migration of the humeral head on plain radiographs after shoulder arthroplasty. The average rate of medial migration in the shoulders in this study was small.

Angelchik prosthesis with oesophageal adenocarcinoma: our surgical approach

The Angelchik prosthesis is an incomplete doughnut-shaped device composed of silicone elastomer used in the treatment of gastro-oesophageal reflux disease (GORD). It is used to encircle the lower oesophagus at the gastro-oesophageal junction (GOJ). The ease of the operation led to the insertion of over 25,000 such prostheses world-wide. However, a variety of major complications including intractable dysphagia, prosthesis migration and gastric erosion required a quarter of these devices to be removed. Development of adenocarcinoma in patients with Angelchik prosthesis is a rare occurrence. This article describes two patients who developed adenocarcinoma above their prosthesis and whose cardio-oesophagectomy was technically challenging due to the formation of a dense inflammatory capsule around the prosthesis. Our surgical approach to curative oesophageal resection with the Angelchik prosthesis in situ is also discussed.

Custom-made lateral femoral condyle replacement for traumatic bone loss: A case report

We report the case of a 24 year-old patient who underwent a novel treatment for a lateral femoral condyle fracture. The fracture was associated with extensive joint line depression and not considered suitable for conventional fixation techniques. Existing reconstructive options for such situations include unicondylar osteoarticular allograft, arthrodesis and arthroplasty. However, these techniques all present significant disadvantages, particularly in the management of active patients. We report our medium-term results following reconstruction using a custom-made lateral femoral condyle hemiarthroplasty replacement. Follow-up at 48 months revealed an excellent, pain-free level of function, with an Oxford Knee Score of 46/48, a Knee Society knee score of 87/100 and a functional score of 100/100. Radiographs demonstrated no evidence of prosthesis loosening or migration and no erosion of the lateral tibial plateau. The technique allows preservation of the remaining normal joint surface of the femur that may promote earlier and better restoration of function. Furthermore, the isolated condyle hemi-replacement maximises bone preservation, facilitating future anticipated revisions. The procedure presents an attractive alternative to other surgical options and their attendant problems. Further investigation into this technique is required before widespread adoption, though such studies will be compromised by the relative rarity of patients in whom the technique is indicated.

Is transapical aortic valve implantation really less invasive than minimally invasive aortic valve replacement?

Transcatheter valve implants currently draw their justification for use from reduction of perioperative risk. However, patient age and comorbidities are independent predictors of adverse outcome after aortic valve replacement, regardless of surgical approach. Therefore, it is unclear whether transapical aortic valve implantation really improves outcomes in high-risk patients. We included a total of 51 high-risk patients with severe aortic valve stenosis. Patients were allocated to transapical aortic valve implantation (n = 21) or minimally invasive aortic valve replacement via a partial upper sternotomy (n = 30), in a nonrandomized fashion. Patient age, preoperative comorbidities, and perioperative risk, expressed as logistic EuroSCORE (38% +/- 14% vs 35% +/- 9%), were matched between the 2 groups. Early morbidity and mortality were comparable between groups, but transapical aortic valve implantation was associated with shorter operative time (P = .004), ventilation time (P < .001), intensive care unit stay (P < .001), and hospital stay (P < .001). Thirty-day mortality was 14% (n = 3) in the transcatheter group versus 10% (n = 3) in the surgical group. After a mean follow-up of 12 +/- 4 months (100% complete), there were a total of 5 (24%) deaths in the transapical group versus 5 (17%) deaths in the open surgery group. There was 1 intraoperative death in the transapical group versus none in the surgery group. In the transapical group, there were 2 re-explorations for bleeding, 2 intraoperative conversions, 1 case of prosthesis migration, and 2 impairments of coronary arteries. The surgery group included 1 re-exploration, 1 stroke, 1 pacemaker implantation for complete atrioventricular block, and 3 cases of atrial fibrillation. Current data suggest a faster postoperative recovery after transapical aortic valve implantation, with early and late morbidity and mortality comparable with those of minimally invasive aortic valve replacement via partial upper sternotomy.

The short-term effects and complications of resurfacing arthroplasty of the hip.

Objective To evaluate the short-term effects and complications of resuffacing arthro-plasty of the hip (RSAH). Methods Twenty-six cases (32 hips) treated with RSAH were analyzed retro-spectively. There were 14 males and 12 females, with a mean age of 46.8 years (range, 30-62 years). Nine cases (11 hips) were diagnosed as developmental dysplasia of the hip, 7 cases (9 hips) as osteonecrosis of the femoral head, 3 cases (4 hips) as ankylosing spondylitis, 5 cases (6 hips) as rheumatoid arthritis, 1 case (1 hip) as osteoarthritis, 1 case (1 hip) as pigmented villonodular synovitis. All cases were checked by MR or CT scan for observing the structure of the acetabulum and femoral head, osteolysis, osteosclerosis as well as the location of necrosis. The X-ray film was performed before operation and after operation (1 month, 3 months and every 6 months) to check the prosthesis loosening, migration and heterotopic ossification. Harris hip score system was used to evaluate the clinical results. Results All cases were followed up 8 months to 4.3 years (average, 2.1 years). The follow-ups showed that Harris scale increased from (44.5±7.1) points pre-operatively to (94.3±5.2) points postoperatively, with 28 hips (87.5%) excellent, 4 hips (12.5%) good. Com-plications consisted of 1 hip femoral nerve injury, 2 cases (3 hips) heterotopic ossification, 2 hips Trendelen-burg gait, 2 hips snapping hip, 1 case deep venous thromboembolism in the lower extremities, 1 hip femoral neck narrowing. There were not femoral neck fracture, infection, dislocation, and prosthesis loosening during our follow-up. Conclusion The RSAH has a satisfactory short-term effect. Mastering the indications and accurate procedure of the operation may help to avoid the complications. Key words: Arthroplasty; replacement; hip; Postoperative complications; Treatment outcome

Biomechanische Analyse der Lendenwirbelsäule nach Implantation einer Bandscheibenendoprothese sowie ergänzender Spondylodese als Komplikationsmanagement

The aim of our investigations was to study the question as to what extent the mono- and multisegmental mobility of the lumbar spine (LS) differs after implantation of a disc prosthesis (DP) and if, in case of postoperative complications (dislocation or migration of the disc prosthesis), a sufficient stability of the motion segment can be achieved with a spinal fusion. To answer these questions we examined in corpse the mobility of the LS before and after DP implantation as well as after spinal fusion by using a load simulator for mobility and stability investigations of the lumbar spine. After radiological exclusion of higher degenerative changes (X-ray in two planes) and exclusion of high-grade osteoporosis by using a pQ-CT scan with measurement of the bone mineral density (T score > -3.0), the first step was the multisegmental measurement of the thirteen unfixated LS specimens without DP by automatic electromechanical load-bearing. The measurements of mobility of the LS were done in flexion, extension, side-bending and side-rotation with a reproducible load of 10 Nm. The analysis of the movements during flexion and extension as well as side-bending and side-rotation were done by an ultrasonic detection system (zebris). In the second step the excursions were measured after implantation of the DP in L3/4 and in the third step after additional dorsal spinal fusion. After implantation of the artificial disc in L3/4 the mobility in side-bending and side-rotation increases in comparison to the LS without surgery. For side-bending we found an increasing amount up to +74 % for the single motion segment L3/4 and +3 % for the total LS, respectively, for the side-rotation an increase of mobility up to +72 % for the single motion segment L3/4 and +30 % for the total LS. On the other hand a decreased mobility of -11 % for flexion and extension was found with an artificial disc in comparison to the lumbar spine. After additional dorsal spinal fusion of L3/4 the mobility obviously decreases in all directions (flexion/extension -74 %, side-bending -75 %, side-rotation -51 %). The DP preserves (flexion/extension) and, respectively, improves (side-rotation/side-bending) the mobility of the LS. In cases of complications like dislocation or migration of the DP and secondary degenerative changes, the dorsal spinal fusion with restricted movements of the LS afterwards is a possible treatment solution.

Feasibility of transapical aortic valve implantation fully guided by transesophageal echocardiography

In our case, AR was actually due to the sequelae of endocarditis and not to structural valve degeneration. Technical issues for TAVIin patients with stentlessbioprostheses are different from thoseinpatientswithnativeaorticstenosis or a stented bioprosthesis. Positioning may be more difficult because of the absence of calcification, and the role of concomitant TEE should be emphasized. The absence of calcification or stents may also theoretically increase the risk of prosthesis migration because of potentially less stable anchorage on the aortic annulus. However, this report illustrates the feasibility of TAVI in patients with severe dysfunction of a stentless bioprosthesis. Valve-in-valve implantation may represent a promising opportunity for the future, 5 inasmuch as limited durability is the major concern of stented or stentless bioprostheses. Further studies including a large number of patients and longer follow-up arerequiredtodefinethe exactroleofTAVIin elderly patients with a degenerated bioprosthesis that requires reintervention.