Treatment of a neglected pseudarthrotic multifragmentary intra-articular supracondylar femoral fracture using a modular reconstruction system

Abstract The standard treatment of acute distal femoral fractures consists of open anatomic reconstruction and fixation. Internal fixation may be accomplished with angular plates, condylar screw fixation, antegrade or retrograde nailing. Inveterated condylar fractures are rarely seen in our society and present challenging management problems. A 64-year-old man presented with a pseudarthrotic dislocated multifragmentary supracondylar fracture and a knee flexion contracture two years following the accident, mobilized only with a wheelchair. Because of the severly osteoporotic bone, degenerative articular changes and the flexion contracture, we chose resection of the fragments and implantation of a reconstruction system (MUTARS) instead of osteosynthesis. Eleven weeks postoperatively, the patient was able to walk without crutches. Nine months after surgery, he has flexion up to 90° and full extension, and has regained an active life.     

模块分叉支架型血管重建犬主动脉弓的可行性研究

目的设计制作腔内重建犬主动脉弓的模块分叉支架型血管,研究其腔内重建主动脉弓的可行性。方法全组10例动物,主动脉造影测量升主动脉、主动脉弓及其分支血管的相关数据,设计并制作适合于重建犬主动脉弓的模块分叉支架型血管;在X线透视引导下,依次自右锁骨下动脉、左锁骨下动脉及股动脉植入支架型血管的三个模块,并在体内对接,完成主动脉弓的重建;观察移植物形态结构、主动脉血流动力学变化及内漏发生状况。结果8例成功完成各模块的植入,另2例分别于术中死于冠状动脉被封堵和左锁骨下动脉破裂。成功完成介入操作的8例动物术中造影结果显示移植物位置及形态良好,冠状动脉及颈总动脉血流通畅,其中2例发现近端I型内漏。结论应用模块分叉支架型血管腔内重建犬主动脉弓在技术方案上是可行的;对腔内重建人体主动脉弓的研究具有指导意义。     

组配式人工半骨盆假体重建的生物力学分析

目的 探讨组配式人工半骨盆假体重建后骨盆生物力学改变及假体力学结构特点.方法 (1)建立正常骨盆的三维有限元模型和离体试验骨盆模型.于骨盆表面选取8个特征测点,在相同的载荷及边界条件下,利用有限元模型计算测点表面应力(σFEM),通过离体试验测量测点应变值,并计算标本表面应力(σEXP).对σFEM和σEXP进行线性回归分析验证.(2)利用验证的正常骨盆有限元模型进行左侧骨盆缺损(Ⅱ+Ⅲ区)及人工假体重建模型的建模.计算重建骨盆健侧特征测点的表面应力(σRS)及患侧髂骨截骨处内、外侧皮质表面应力(σRR),分别与正常骨盆相同位置测点应力值(σNS,σNR)进行比较.(3)分析假体应力传导结构表面应力分布特点及应力集中部位.结果 (1)骨盆有限元计算结果 与离体试验结果 有良好的一致性(R~2=0.87),模型仿真度较高.(2)重建后健侧特征测点σRS与正常骨盆σNS近似(t=1.81,P=0.08).患侧髂骨截骨处内侧皮质σRR与σNR差异无统计学意义(t=0.47,P=0.65),外侧皮质σRR明显高于σNR(t=2.78,P=0.02).(3)假体应力传导结构主要由后侧传导.应力集中部位位于下排钉孔周围、髂骨固定座与侧面固定翼片连接处、人工髋臼与髂骨固定连接处,系统应力峰值(183 MPa)位于人工髋臼与髂骨固定座连接部位.结论 组配式人工半骨盆假体重建符合骨盆生物力学特点,较好地恢复了应力传导.     

组配式人工半骨盆假体重建的生物力学分析

Objective To analysis the biomechanical characteristics of the reconstructed pelvis with modular hemi-pelvie prosthesis by finite element (FE) method. Methods A subject-specific finite element model of pelvis was established. Th experiment was performed on the same cadaveric pelvis. Eight points on the surface of cortical bone was determined. Both the same load and boundary conditions were applied on the FE model and experiment. The stress by experiment (σ EXP) was calculated based on the data collected from the strain discs. Linear regression was performed with the stress predicted by FE model (σFEM) and experi-ment data to validate the FE model. A defect pelvic (with zone Ⅱ +Ⅲ in left hemi-pelvis) FE model was con-structed and assembled with the prosthesis. The stress distribution on the eontra lateral hemi-pelvis was cal-culated by the reconstructed pelvic FE model (σRS), and the results were compared with that of the normal pelvis (σNS). Also the comparison was clone at the resection level of the affected hemi-pelvis between normal pelvic FE model (σNR) and reconstructed model (σRR) both on medial and lateral cortical bone of the pelvis. Structural analysis was performed on the whole set of implant. Results FE predictions were strongly correlated with experimental results (R2=0.87). No significant difference was found between the σRS and σNS (t=1.81, P=0.08). Regarding to the stress distribution at lilac resection level, no difference was found between σNR and σRR on the medial side (t=0.47, P=0.65). However, on the lateral side, σRR were signifi-cantly higher than the σNR (t=2.78, P=0.02). The peak stress of the prosthesis was about 183 MPa located at the conjunction of the acetabulum and the iliac fixation part. The main load conduction path on the prosthe-sis was at the posterior side of column portion part of the iliac fixation. Conclusion Reconstruction with modular hemi-pelvic prosthesis could recover the pelvic biomechanics with rational mechanical design.     

Revision total hip: a novel modular cementless acetabular system for reconstruction of severe acetabular bone loss

Severe acetabular bone loss remains a challenge at the time of revision hip arthroplasty. A novel modular system is available to aid in the reconstruction of these challenging cases. This technique can provide support for an uncemented acetabular shell. By using the augments in combination with the revision acetabular component, the following goals of revision surgery on the acetabular side can be achieved at the time of surgery: initial stable fixation, restoration of the center of rotation, and maximization of host bone contact.     

A modular spinal rod linkage system to provide rotational stability

The effect of cross linkage on the in vitro stability of paired Harrington distraction rods was studied in an unstable fracture model using calf spine segments. Cross linkage used in conjunction with sublaminar wires significantly improved torsional stability, improved lateral bending stability, and had no adverse affect on stability for axial, forward flexion, or extension loading compared to rods alone, rods with bridges, and wired rods.     

Medial reconstruction technique in the treatment of complex fractures of humeral proximal epiphysis with SMR prosthetic modular system

Prosthetic treatment of complex fractures of humeral proximal meta-epiphysis is a very complex surgery that often does not lead to satisfactory results. Indeed, although in the last 35 years since Neer’s studies some progress has been made in the knowledge of the anatomy of humeral meta-epiphysis proximal portion, surgical technique and prosthetic design, in the literature we find non-homogeneous experiences regarding the clinical-functional results. At the same time, such experiences agree as far as pain relief is concerned. We report our experience in the treatment of complex fractures of humeral proximal epiphysis with SMR (Lima Lto, San Daniele, Italy) prosthetic system, using our surgical technique of anatomical reconstruction, starting from the medial neck. The case histories, 35 patients, 30 women and 5 men, aged between 56 and 79, were reported in the observation period between April 2000 and February 2005. In 20 cases the right shoulder was treated and in 15 the left one. At the follow-up the patients were assessed clinically by the average Constant Score and also by X-rays and CT scan in order to measure the prosthesis height, its off-set and retroversion.     

A modular retraction system (VarioLift) for laparoscopy without pneumoperitoneum

Because of adverse physiological effects and technical disadvantages of the pneumoperitoneum, alternative methods of abdominal wall lifting have been explored recently. Most of these systems are complicated in their system set-up and handling or the intraabdominal exposure is limited. The modular retraction system (VarioLift, AESCULAP Tuttlingen) consists of two different components, one for the abdominal wall lifting, and one for internal organ compression. Via a 2 cm mini-laparotomy two lifting parts of different size and shape are introduced into the abdominal cavity, assembled to each other and attached to an outside mechanical lifting arm which is suspended to the operating table. Using combinations of these parts, the system can be adjusted to different abdominal quadrants and the patient's individual anatomy. According to the needs of vision for internal organ compression a translucent plastic membrane can be placed for posterior organ retraction using the same access. In contrast to other systems the modular retraction system (VarioLift) allows an individual adjustment to the patient's anatomy and, if necessary, compression of internal organs. A planar suspension of the abdominal wall with a good lateral exposure and a dome-shaped suspension without tenting effects is provided. Time needed for mini-laparotomy and system set-up is only slightly longer than installation of a pneumoperitoneum.     

Finite element analysis of the pelvis after modular hemipelvic endoprosthesis reconstruction

Purpose

The aim of this study was to investigate the biomechanics of the pelvis reconstructed with a modular hemipelvic prosthesis using finite element (FE) analysis.

Methods

A three-dimensional FE model of the postoperative pelvis was developed and input into the Abaqus FEA software version 6.7.1. Mesh refinement tests were then performed and a force of 500 N was applied at the lamina terminalis of the fifth lumbar vertebra along the longitudinal axis of the normal pelvis and the postoperative pelvis for three positions: sitting, standing on two feet, and standing on the foot of the affected side. Stress distribution analysis was performed between the normal pelvis and postoperative pelvis at these three static positions.

Results

In the normal pelvis, stress distribution was concentrated on the superior area of the acetabulum, arcuate line, sacroiliac joint, sacral midline and, in particular, the superior area of the greater sciatic notch. In the affected postoperative hemipelvis, stress distribution was concentrated on the proximal area of the pubic plate, the top of the acetabular cup, the connection between the CS-fixator and acetabular cup and the fixation between the prosthesis and sacroiliac joint.

Conclusions

Stress distribution of the postoperative pelvis was similar to the normal pelvis at three different static positions. Reconstruction with a modular hemipelvic prosthesis yielded good biomechanical characteristics.     

Disassembly of a Howmedica modular resection system

We report the postoperative disassociation of a Morse taper junction of a Howmedica Modular Resection system implanted after the resection of a malignant distal femoral bone tumor. The disassembly occurred without apparent trauma. This complication was managed by closed reduction under epidural anesthesia. This disassembly probably occurred because of decreased tension of the soft tissue around the prosthesis or an impaired locking mechanism.     

Experience with modular system tumor prostheses]

Authors elaborated a modular tumor prosthesis by the use of which the bone segment lost after the resection of hip, femur, knee and proximal tibial tumors can be supplemented in the desired measure. The components of the prosthesis set and the field of its use are described. In the last one and half year modular tumor prostheses were inserted in 10 patients: in 6 primary bone tumors and 4 solitary metastases. One shoulder, 5 hip, 3 stiff knee and 1 tibia diaphysis supplementing modular prostheses were inserted. In spite of 2 complications the initial experiences are encouraging, and in adequate indication the possibility of retaining limb and articular function beside good functional results is given.     

Management of septic complications following modular endoprosthetic reconstruction of the proximal femur

In a retrospective single-centre study 170 consecutive patients were included who received a Kotz modular prosthesis after resection of bone tumours of the proximal femur to evaluate the management of prosthetic infection. Infection occurred in 12 of 166 patients available for follow-up (six males; six females; mean age, 47 years; range, ten to 75 years) after a mean of 39 months (range, one to 166 months; infection rate, 7.2%). Mean follow-up was 54 months (range, four to 200 months). One patient died of septic shock. Two patients were treated by wound revision only. Treatment of infection in the remaining patients was one-stage revision in eight and hip disarticulation in one. Infection control by one-stage revision was achieved in five of eight patients; re-infection occurred in three patients and was successfully treated by further revision in all of them. The overall success rate for controlling infection was 83.3%.     

Outcome after pelvic sarcoma resection and reconstruction with a modular hemipelvic prostheses

Purpose  

The aim of this study was to evaluate the early clinical outcome of reconstruction with modular hemipelvic prostheses after pelvic sarcoma resection.     

A new modular testing system for biomechanical evaluation of tibial intramedullary fixation devices

This biomechanical study was performed to evaluate a new modular, tibial testing system developed for analysis of tibial nails and their locking screws.A new testing system, consisting of five modules, was designed to simulate a tibia. For this study one module was removed to simulate a 55-mm distal tibial defect inducing maximum loading on the distal portion of the implant and locking bolts. The tibial load offsets were 23 mm proximally and 10 mm distally medial to the centreline of the tibial shaft to simulate the location of the expected resultant load during the peak loading and inversion torque on the ankle during the gait cycle. Four solid tibial nails (STN, Stryker-Howmedica-Osteonics, Kiel, Germany) were tested to static failure and 15 nails were tested dynamically.Our results showed that the solid tibial nails fractured in the testing device in the same manner and location as they do in clinical series. Evaluation of the results showed the mean fatigue limit of the STN to be 1.4 kN for 500,000 cycles with a standard deviation (S.D.) of 0.33 kN.This biomechanical study establishes a standard technique for the biomechanical testing of tibial nails, in a clinically relevant manner, avoiding the inconsistency of cadaver bone tests. As it is a standardised test set-up this new modular testing system could serve as a standard by which small diameter tibial nails and other devices could be evaluated and compared with other systems currently in use.     

Cemented hip prostheses: modular screw system.

The long-term results of 21 patients treated with modular screw cementless hip prostheses are reported. An examination of periprosthetic osteogenesis and function evaluated by gait analysis revealed good incorporation of the prosthesis and good clinical results in all of the cases studied.