Lukas Konstantinidis

High Complication Rate After Biplanar Open Wedge High Tibial Osteotomy Stabilized With a New Spacer Plate (Position HTO Plate) Without Bone Substitute

PURPOSE We performed a prospective clinical and radiographic evaluation after open wedge high tibial osteotomy (HTO) using the new Position HTO plate (Aesculap, Tuttlingen, Germany) without bone transplantation. METHODS Thirty-five open wedge HTOs with the Position HTO plate were performed without bone wedges. The mean patient age was 44.6 ± 9.2 years at the time of osteotomy, which was planned with mediCAD II software (Hectec, Niederviehbach, Germany). The Hospital for Special Surgery score, Lysholm-Gillquist score, Tegner activity level, and International Knee Documentation Committee subjective score were used for clinical assessment. We evaluated radiographs obtained preoperatively and at 2, 6, and 12 months postoperatively using full-weight-bearing anteroposterior whole-leg views and anteroposterior and lateral views of the knee. For statistical analyses, JMP 8.0.1 (SAS, Cary, NC) was used. RESULTS We observed an overall complication rate of 34% and a plate-related complication rate of 23%. Plate-related complications included loss of correction, fracture of the tibial plateau, screw failure, malunion, and fracture of the lateral cortical bone. A significant difference in the mechanical tibiofemoral angle of -1.3° ± 1.4° (P < .001) was found between the follow-up at 2 and 6 months. The mean Hospital for Special Surgery score was 74.8 ± 11.7 preoperatively, and it increased to 87.8 ± 11.0 (P < .001). The mean score on the Lysholm-Gillquist knee functional scoring scale was 55.5 ± 21.7 preoperatively, and it improved to 73.0 ± 23.9 (P < .001). The Tegner activity level was 2.6 ± 0.9 preoperatively, and it improved significantly at final follow-up to 3.7 ± 1.8 (P < .02). The International Knee Documentation Committee subjective score was 43.0 ± 14.9 preoperatively, and it increased to 66.1 ± 21 (P < .001). CONCLUSIONS We have shown a high plate-related complication rate and a significant loss of correction between 2 and 6 months of follow-up after open wedge HTO using the new Position HTO plate without bone wedges. The preoperatively planned mechanical tibiofemoral angle was not achieved. Despite these complications, the clinical outcome improved significantly. The Position HTO plate cannot be recommended with the presented technique. LEVEL OF EVIDENCE Level IV, therapeutic case series.

Treatment of periprosthetic femoral fractures with two different minimal invasive angle-stable plates: Biomechanical comparison studies on cadaveric bones

INTRODUCTION The introduction of fixed-angle plate osteosynthesis techniques has provided us a further means to treat periprosthetic femoral fractures. The goal of this experimental study is to evaluate the biomechanical properties and stability of treated periprosthetic fractures when using two different plate systems, which vary in the locking mechanism and the screw placement (monocortical or bicortical) with respect to the prosthesis stem. MATERIALS AND METHODS Using five pairs of formalin-fixed femora, a Vancouver B1 periprosthetic fracture was treated either with a 13-hole LISS(®) titanium plate using four monocortical periprosthetic screws or with a non-contact bridging plate (NCB) DF(®) plate using bicortical angle-stable blocked screws positioned ventrally or dorsally to the prosthesis stem. Bones were loaded under axial and cyclic compression with a progressively increased load until failure. Displacement at the osteotomy gap was measured during loading using an ultra-sound measuring system. RESULTS The mean displacement in the region of the fracture gap was not significantly different at any time during the experiments for the two models. The mean force resulting in subsequent model failure was similar in both models; the failure morphology varied slightly between the models, however. Four of the five LISS(®) models exhibited either a tear-out of the monocortical screws or a decortication from the bony shaft of the cortical lamella surrounding the screws. On the other side, two of the NCB models showed macroscopically visible fissures along the osteosynthesis plates at the height of the osteotomy gap, and were hence considered implant failures. Only one NCB model showed tear-out of the bicortically placed screws. CONCLUSION Bicortical screw placement provides more stable anchoring when compared to monocortical screw fixation. However, in relation to the amount of motion at the osteotomy gap and to failure loads, stabilisation of periprosthetic femoral fractures can be equally well achieved using either the LISS(®) plate with periprosthetic monocortical screws or the NCB plate with poly-axially placed bicortical screws.

Finite element analysis of four different implants inserted in different positions to stabilize an idealized trochanteric femoral fracture

Biomechanical analysis of the ideal placement of new intramedullary implants for stabilization of trochanteric fractures is not currently available. The aim of the presented study is to determine to what extent four intermedullary nails (Gliding-Nail, Gamma-Nail, PFN-A and Targon-PF), inserted in different positions, differ mechanically. A proximal femur was reconstructed on the basis of clinical CT data as a surface model. Load application equivalent to the one-leg stance phase during gait was assumed, taking into account a limited number of active muscle forces. The four implants were inserted cranially and caudally into the bone structure and a model of a trochanteric fracture was created. Criteria with point ratings were introduced to quantify a favourable fracture healing situation. Finite element simulation showed clear differences between the different implants with regard to the distributions of stress and strain at the two fracture surfaces in the model and the von Mises stress in the implant itself. It was apparent for three implants under investigation that the caudal position generated better fracture healing conditions than the cranial position. Only the Targon PF demonstrated better fracture healing conditions in the cranial position. Evaluation based on the point rating system revealed that the caudal position was the ideal position for the PFN-A, Gamma-Nail and Gliding-Nail. The Targon-PF demonstrated some advantages over the other implants in the caudal position.

Do changes in dynamic plantar pressure distribution, strength capacity and postural control after intra-articular calcaneal fracture correlate with clinical and radiological outcome?

UNLABELLED Fractures of the calcaneus are often associated with serious permanent disability, a considerable reduction in quality of life, and high socio-economic cost. Although some studies have already reported changes in plantar pressure distribution after calcaneal fracture, no investigation has yet focused on the patients strength and postural control. METHOD 60 patients with unilateral, operatively treated, intra-articular calcaneal fractures were clinically and biomechanically evaluated >1 year postoperatively (physical examination, SF-36, AOFAS score, lower leg isokinetic strength, postural control and gait analysis including plantar pressure distribution). Results were correlated to clinical outcome and preoperative radiological findings (Böhler angle, Zwipp and Sanders Score). RESULTS Clinical examination revealed a statistically significant reduction in range of motion at the tibiotalar and the subtalar joint on the affected side. Additionally, there was a statistically significant reduction of plantar flexor peak torque of the injured compared to the uninjured limb (p<0.001) as well as a reduction in postural control that was also more pronounced on the initially injured side (standing duration 4.2±2.9s vs. 7.6±2.1s, p<0.05). Plantar pressure measurements revealed a statistically significant pressure reduction at the hindfoot (p=0.0007) and a pressure increase at the midfoot (p=0.0001) and beneath the lateral forefoot (p=0.037) of the injured foot. There was only a weak correlation between radiological classifications and clinical outcome but a moderate correlation between strength differences and the clinical questionnaires (CC 0.27-0.4) as well as between standing duration and the clinical questionnaires. Although thigh circumference was also reduced on the injured side, there was no important relationship between changes in lower leg circumference and strength suggesting that measurement of leg circumference may not be a valid assessment of maximum strength deficits. Self-selected walking speed was the parameter that showed the best correlation with clinical outcome (AOFAS score). CONCLUSION Calcaneal fractures are associated with a significant reduction in ankle joint ROM, plantar flexion strength and postural control. These impairments seem to be highly relevant to the patients. Restoration of muscular strength and proprioception should therefore be aggressively addressed in the rehabilitation process after these fractures.

Digital templating in total knee and hip replacement: an analysis of planning accuracy.

PurposeThe aim of this study was to determine how well pre-operative size selection for total knee and hip arthroplasties based on the digital imaging with and without additional referencing correlated with the size actually implanted.MethodsSize selection planning of total knee arthroplasty by digital templating was documented in 46 cases with reference ball (group A) and in 48 cases without ball (group B). In addition, prospective analysis of pre-operative planning was conducted for 52 acetabular components with reference ball (group C) and 69 without ball (group D) as well as stem planning in 38 cases with ball (group E) and 54 cases without ball (group F). The data were analysed and compared with the size of the final component selected during surgery.ResultsThe correlation between planned and implanted size for total knee arthroplasty in group A resulted in femoral anteroposterior (AP) r = 0.8622 and lateral r = 0.8333 and in group B AP r = 0.4552 and lateral r = 0.6950. Tibial in group A was AP r = 0.9030 and lateral r = 0.9074 and in group B AP r = 0.7000 and lateral r = 0.6376. For the acetabular components, the results in group C were r = 0.5998 and group D r = 0.6923. For stems, group E was r = 0.5306 and group F r = 0.5786. No correlation between BMI and the difference between planned and implanted size was found in any of the groups.ConclusionIn the case of total hip arthroplasty there was a relatively low correlation between planned and implanted sizes with or without reference ball. For total knee arthroplasties the already high precision of size planning was further improved by the additional referencing with a reference ball.

Effects of three-dimensional navigation on intraoperative management and early postoperative outcome after open reduction and internal fixation of displaced acetabular fractures.

BACKGROUND This study was conducted to evaluate whether intraoperative procedure and/or early postoperative results after open reduction and internal fixation (ORIF) of displaced acetabulum fractures are influenced by the use of a three-dimensional (3D) image intensifier in combination with a navigation system. METHODS From January 2004 until December 2008, all patients with acetabular fractures were followed prospectively. From January 2004 until October 2006, all operations were performed under fluoroscopic control using a conventional two-dimensional image intensifier. Since October 2006, we regularly operate acetabular fractures with the intraoperative use of a navigation system and a 3D image intensifier. Pre- and postoperative computed tomography scans of the affected hip were obtained in all patients as were standard anterior-posterior radiographs and ala- and obturator views. All data collection was performed according to the guidelines of the “German Pelvic fracture study group.” RESULTS In total, 68 patients with acetabular fractures were included in the study. A conventional image intensifier was used in 37 patients (group A) and a 3D image-based navigation was used in the remaining 31 patients (group B). In the navigated group, seven patients were assessed incapable of partial weight bearing. These patients underwent computer-assisted percutaneous screwing of their acetabular fracture. Using a navigation system in combination with a 3D image intensifier for ORIF of displaced acetabular fractures led to a significant increase in skin-to-skin time. Postoperative radiolographic analysis revealed an improvement in the quality of fracture reduction in the 3D navigation group. Navigation in combination with the 3D images of the ISO-C 3D limited the need for extended approaches. In addition, the complication rate in the navigated group was significantly lower. CONCLUSION We support the use of navigation systems and a 3D image intensifier as helpful tools during ORIF of displaced acetabular fractures. LEVEL OF EVIDENCE Therapeutic study, level III.

Intramedullary nailing of trochanteric fractures: central or caudal positioning of the load carrier? A biomechanical comparative study on cadaver bones

BACKGROUND Current recommendations with regard to central or caudal positioning of the femur head carrier in the management of trochanteric fractures are contradictory. METHODS A standardised pertrochanteric osteotomy was stabilised in 15 pairs of cadaver femurs by means of intramedullary osteosynthesis (5xPFN-A-Synthes, 5xIntertan-Smith&Nephew, 5xTargon-PF-Aesculap). For each pair randomised central (group A) or caudal (group B) implantation of the femoral neck component was performed. Subsequently, the constructs were axially loaded to 2100N. In the absence of cut out after 20,000 cycles, load was increased to a maximum force of 3100N. Angular displacement was recorded based on ultrasound. Migration of the load carrier in the femoral head was monitored radiologically. FINDINGS DISPLACEMENT No significant difference between groups (p>0.15) was found for the first 50 load cycles. A significantly greater degree of varus deformity was observed in group A (p=0.049) after 2000 load cycles and became more apparent as the number of load cycles increased (after 6000 cycles p=0.039, after 20,000 cycles p=0.034, after 22,000 cycles p=0.016). Angular displacement in the other two planes did not differ significantly across groups. CUT OUT: Migration of the load carrier in the femoral head was not significantly different for the two groups. Overall cut out occurred in 9 constructs, 3 in group A and 6 in group B. The difference in cut-out rate was not significant (p=0.213, chi-squared test). CONCLUSION Biomechanical superiority can be shown for caudal positioning of the femoral neck load carrier in terms of reduced varus deformity. The incidence of cut out is however unaffected by the position of the load carrier.

Salvage procedures for trochanteric femoral fractures after internal fixation failure: biomechanical comparison of a plate fixator and the dynamic condylar screw.

The aim of this study was the biomechanical evaluation of the reversed less invasive stabilization system (LISS) internal fixation as a joint-preserving salvage procedure for trochanteric fractures. Five LISS plates and five dynamic condylar screws (DCS) were tested using synthetic femora (Sawbones®) with an osteotomy model similar to a type-A2.3 pertrochanteric fracture. The constructs were subjected to axial loading up to 1000 N for five cycles. Then, the force was continuously increased until fixation failure. For the evaluation of the biomechanical behaviour, the stiffness levels were recorded and the osteotomy gap displacement was mapped three-dimensionally. The average stiffness for the constructs with LISS plates was 412 N/mm (with a standard deviation (SD) of 103N/mm) and 572 N/mm (SD of 116 N/mm) for the DCS constructs (p = 0.051). Local displacement at the osteotomy gap did not yield any significant differences. The LISS constructs failed at a mean axial compression of 2103 N (SD of 519 N) and the DCS constructs at a mean of 2572 N (SD of 372 N) (p = 0.14). It is concluded that the LISS plate offers a reliable fixation alternative for salvage procedures.

Early surgery-related complications after anteroposterior stabilization of vertebral body fractures in the thoracolumbar region

BackgroundThe complication rate after trauma-associated spine surgery remains unknown because of the rarity of this injury and the polymorphism of treatment methods. We report the complication rates recorded at one center after treatment of unstable vertebral body fractures according to a single, uniform procedure. The aim of this analysis was to identify the typical complications associated with this surgical procedure and, consequently, to contribute to critical deliberations on the introduction of technical innovations such as navigation, intraoperative three-dimensional imaging, and neuromonitoring.MethodsPerioperative complications related to surgery of 208 consecutive patients, operated on for unstable vertebral body fractures were analyzed. First, stabilization was performed through an open, posterior, nonnavigated approach. This was followed, in all patients, by reconstruction of the anterior column form with a tricortical iliac crest graft during a second operation.ResultsIn regard to posterior stabilization, at least one pedicle screw in six patients (3%) was placed incorrectly; furthermore, there were five patients with general complications, all of which required revision surgery. After anterior spondylodesis, there were also nine general complications and five neurological complications, one of them in a patient with persistent paraplegia. At the graft donor site, three patients experienced an avulsion fracture of the anterosuperior iliac crest. Overall, at least one complication occurred in 13% of patients (confidence interval 0.08–0.18).ConclusionsWith regard to early complications, two-stage anteroposterior stabilization of unstable spinal fractures of the thoracolumbar spine is a reliable procedure.

Effects of muscle-equivalent forces on the biomechanical behavior of proximal femur fracture models: a pilot study on artificial bones

Introduction: There has been extensive analysis of the influence of muscle forces and their effects on the biomechanical behavior of the proximal femur. Nevertheless, these forces have only been taken into account in a handful of biomechanical studies in the field of traumatology. The aim of this study was to analyze the biomechanical behavior of two typical fracture models of the proximal femur based on muscle-equivalent forces. Method: Plate osteosynthesis was performed on two groups of artificial femora to stabilize either a trochanteric osteotomy (n = 5) or a femur shaft osteotomy (n = 5). After fixation axial loading was applied to the constructs first without muscle-equivalent forces and then with the addition of these forces (abductor groups and vastus lateralis). Displacement at the osteotomy site and the stiffness of the whole construct were measured during loading. Results: Comparison of the two loading modes revealed no significant differences for displacement or stiffness for the trochanteric fractures. For the femur shaft fractures, a significant difference was found for displacement (p = 0.023) and stiffness (p = 0.003) with or without muscle-equivalent forces. Conclusion: The loading protocol for implant testing on femur shaft fractures should include muscle-equivalent forces. For trochanteric fractures, consideration of muscle forces is not entirely necessary since they will have little effect on the results, for example, when comparing implants.