Clemens Kösters

Medial Patellofemoral Ligament Reconstruction: Fixation Strength of 5 Different Techniques for Graft Fixation at the Patella

PURPOSE To compare the structural properties of 5 different fixation strategies for a free tendon graft at the patella in medial patellofemoral ligament (MPFL) reconstruction under cyclic loading and load to failure testing. METHODS We used porcine patella and flexor tendons. We tested the following fixation techniques: 3.5-mm titanium anchor, transosseous 1-mm braided polyester suture, interference screw fixation, medial bone bridge, and transpatellar tunnels. We preconditioned each graft between 5 and 20 Nm before cyclic loading with 100 Nm for 1,000 cycles was started, and then performed load to failure testing. We recorded maximum load, stiffness, and elongation. RESULTS In the bone bridge group, 60% of all specimens failed during cyclic testing. Fixation by transosseous sutures showed significantly less stiffness compared with all other techniques (P < .05). The bone bridge technique showed significantly lower load to failure compared with all other techniques (P < .05). Differences between the other groups were not significant. CONCLUSIONS Fixation of a free tendon graft by transosseous sutures provides similar load to failure and elongation but less stiffness compared with fixation by anchors, interference screws, or transverse tunnels. Load to failure for the bone bridge technique was significantly lower than that for all other techniques. Furthermore, this fixation technique had a lower load to failure than that of the native MPFL. CLINICAL RELEVANCE Fixation of soft tissue grafts at the patella by 1-mm braided polyester suture provides adequate fixation strength without implants in the patella, which might cause soft tissue irritation. Further studies will have to show if the lesser stiffness of this technique causes problems in the clinical setting or if this laxity might even be an advantage because it makes this reconstruction more forgiving concerning overtensioning the graft. Significantly lower load to failure of the bone bridge technique should be considered in postoperative treatment.

How to enhance the stability of locking plate fixation of proximal humerus fractures? An overview of current biomechanical and clinical data

BACKGROUND The complication rate after locking plate fixation of proximal humerus fractures is high. In addition to low bone mineral density, a lack of medial support has been identified as one of the most important factors accounting for mechanical instability. As a result of the high failure rate, different strategies have been developed to enhance the mechanical stability of locking plate fixation of proximal humerus fractures. The aim of the present article is to give an overview of the current biomechanical and clinical studies that focus on how to increase the stability of locking plate fixation of proximal humerus fractures. METHODS A comprehensive search of the Medline databases using specific search terms with regard to the stability of locking plate fixation of proximal humerus fractures was performed. After screening of the articles for eligibility, they were subdivided according to clinical and biomechanical aspects. RESULTS Medial support screws, filling of bone voids and screw-tip augmentation with bone cement as well as the application of bone grafts are currently the most frequently assessed and performed methods. Although the evidence is weak, all of the mentioned strategies appear to have a positive effect on achieving and maintaining a stable reduction even of complex fractures. CONCLUSION Further clinical studies with a higher number of patients and a higher level of evidence are required to develop a standardised treatment algorithm with regard to cement augmentation and bone grafting. Although these measures are likely to have a stabilising effect on locking plate fixation, its general use cannot be fully recommended yet.

MPFL reconstruction using a quadriceps tendon graft Part 1: Biomechanical properties of quadriceps tendon MPFL reconstruction in comparison to the Intact MPFL. A human cadaveric study

BACKGROUND The aim of this study was to analyze the structural properties of the original MPFL and to compare it to a MPFL-reconstruction-technique using a strip of quadriceps tendon. METHODS In 13 human cadaver knees the MPFLs were dissected protecting their insertion at the patellar border. The MPFL was loaded to failure after preconditioning with 10 cycles in a uniaxial testing machine evaluating stiffness, yield load and maximum load to failure. In the second part Quadriceps-MPFL-reconstruction was performed and tested in a uniaxial testing machine. Following preconditioning, the constructs were cyclically loaded 1000 times between 5 and 50 N measuring the maximum elongation. After cyclic testing, the constructs have been loaded to failure measuring stiffness, yield load and maximum load. For statistical analysis a repeated measures (RM) one-way ANOVA for multiple comparisons was used. The significance was set at P<0.05. RESULTS During the load to failure tests of the original MPFL the following results were measured: stiffness 29.4 N/mm (+9.8), yield load 167.8 N (+80) and maximum load to failure 190.7 N (+82.8). The results in the QT-technique group were as follows: maximum elongation after 1000 cycles 2.1 mm (+0.8), stiffness 33.6 N/mm (+6.8), yield load 147.1 N (+65.1) and maximum load to failure 205 N (+77.8). There were no significant differences in all tested parameters. CONCLUSIONS In a human cadaveric model using a strip of quadriceps-tendon 10 mm wide and 3mm deep, the biomechanical properties match those of the original MPFL when tested as a reconstruction. CLINICAL RELEVANCE The tested QT-technique shows sufficient primary stability with comparable biomechanical parameters to the intact MPFL.

Treatment of proximal humerus fractures with a CFR-PEEK plate: 2-year results of a prospective study and comparison to fixation with a conventional locking plate

BACKGROUND A radiolucent carbon fiber-reinforced polyetheretherketone (CFR-PEEK) plate was recently introduced for fixation of proximal humerus fractures. Prospective clinical and radiographic results of patients treated with a CFR-PEEK plate are compared with those of patients treated with a conventional locking plate. METHODS Twenty-nine patients (mean age, 66 years) were treated with a CFR-PEEK plate for a 3- or 4-part proximal humerus fracture. Patients were clinically and radiographically re-examined at 6 weeks, 6 months, 12 months, and 24 months with the Simple Shoulder Test, Constant-Murley score (CMS), and Oxford Shoulder Score (OSS) as well as with simple radiographs. In addition, results were compared with a matched group of patients treated with a conventional locking plate. RESULTS At the final follow-up examination at 24 months, patients achieved a mean Simple Shoulder Test score of 58%, a mean CMS of 71.3 points (range, 44-97), and a mean OSS of 27.4 points (range, 8-45). Bone union was confirmed in all patients. Compared with patients treated with the conventional locking plate, patients treated with the CFR-PEEK plate achieved significantly better results with regard to the CMS and the OSS (P = .038 and .029, respectively). Furthermore, loss of reduction with subsequent varus deformity was less frequently observed in the CFR-PEEK plate group. CONCLUSION Fixation of proximal humerus fractures with a CFR-PEEK plate provides satisfying clinical and radiographic results after 2 years of follow-up. The results are comparable to those achieved with conventional locking plates.

Dynamische intraligamentäre Stabilisierung frischer Rupturen des vorderen Kreuzbandes (Ligamys)

ZusammenfassungDie Ersatzplastik des vorderen Kreuzbandes (VKB) mittels körpereigener Sehne hat sich als Standardverfahren in der Behandlung der VKB-Ruptur etabliert. Dennoch wurden immer wieder Versuche unternommen, das frisch rupturierte VKB zu nähen. Die Ergebnisse waren jedoch eher enttäuschend. Die dynamische intraligamentäre Stabilisierung (DIS) wurde entwickelt, um die biomechanische Stabilität nach primärer Naht des VKB zu gewährleisten und somit eine stabile Einheilung zu ermöglichen. Im Gegensatz zur einfachen Augmentation mittels nichtresorbierbarer Fäden wird bei der DIS ein Federmechanismus verwendet, um der Anisometrie des VKB gerecht zu werden und die Tibia über den gesamten Bewegungsumfang in der hinteren Schublade zu halten. Erste biomechanische und klinische Studien sind vielversprechend, eine erfolgreiche Wiederherstellung der Kniegelenkkinematik ist möglich. Weitere Studien sind allerdings notwendig, um die Wertigkeit dieses neuen Verfahrens für den klinischen Alltag zu belegen.AbstractAnterior cruciate ligament (ACL) reconstruction with the use of autologous tendon grafts is the gold standard in the treatment of ACL instability; however, many different techniques have been proposed to suture freshly ruptured ACLs. Unfortunately, the rate of recurrent instability is high. A new technique, dynamic intraligamentary stabilization (DIS), was developed to restore biomechanical stability after primary ACL repair and therefore to allow stable healing. In order to compensate for the anisometry of the ACL, in contrast to simple augmentation a spring mechanism is used in DIS that helps to maintain the tibia in a posterior drawer position during all degrees of flexion. Initial results of biomechanical and clinical studies are promising, indicating that reconstruction of knee joint kinematics after ACL repair with DIS is possible; however, further clinical studies are required to determine its usefulness in the clinical setting.

Utilisation of Blood Components in Trauma Surgery: A Single-Centre, Retrospective Analysis before and after the Implementation of an Educative PBM Initiative.

Background: The aim of our single-centre retrospective study presented here is to further analyse the utilisation of allogeneic blood components within a 5-year observation period (2009-2013) in trauma surgery (15,457 patients) under the measures of an educational patient blood management (PBM) initiative. Methods: After the implementation of the PBM initiative in January 2012, the Institute of Transfusion Medicine und Transplantation Immunology educates surgeons and nurses at the Department of Trauma Surgery to avoid unnecessary blood transfusions. A standardised reporting system was used to document the utilisation of blood components carefully for the most frequent diagnoses and surgical interventions in trauma surgery. These measures served as basis for the implementation of an interdisciplinary systematic exchange of information to foster decision-making processes in favour of patient blood management. Results: Since January 2012, the proportion of patients who received a transfusion as well as the number of transfused red blood cell (RBC) (7.3%/6.4%; p = 0.02), fresh frozen plasma (FFP) (1.7%/1.3%; p < 0.05) and platelet (PLT) (1.0%/0.5%; p < 0.001) units were reduced as a result of our PBM initiative. However, among the transfused patients, the number of administered RBC, FFP and PLT units did not decrease significantly. Overall, patients who did not receive transfusions were younger than transfused patients (p = 0.001). The subgroup with the highest probability of blood transfusion administered included patients with intensive care and long-term ventilation (before/after implementation of PBM: RBC 81.5%/75.9%; FFP 33.3%/20.4%; PLT 24.1%/13.0%). Only a total of 60 patients of 531 patients suffering multiple traumas were massively transfused (before/after implementation of PBM: RBC 55.6%/49.8%; FFP 28.4%/20.4%; PLT 17.6%/8.9%). Conclusion: According to our educational PBM initiative, at least the proportion of trauma patients who received allogeneic blood transfusions could be reduced significantly. However, in case of blood transfusions, the total consumption of RBC, FFP and PLT units remained stable in both time periods. This phenomenon might indicate that the actual need of blood transfusions rather depends on the severity of trauma-related blood loss, the coagulopathy rates or the complexity of the surgical intervention which mainly determines the intra-operative blood loss. Taken together, educational training sessions and systematic reporting systems are suitable measures to avoid unnecessary allogeneic blood transfusions and to continuously improve their restrictive application.

Endoprothetik nach Trauma

ZusammenfassungDie Indikation für die Prothesenimplantation nach Trauma ergibt sich in der Regel aus der Schwere und dem Typ der Fraktur sowie dem hohen Alter des Patienten. Somit ist die Ausgangslage für den operativen Eingriff allein aufgrund dieser Bedingungen deutlich schlechter als bei der primären endoprothetischen Versorgung degenerativer Gelenkerkrankungen. Auch die Planung der Operation erfordert eine sensitivere und meist aufwändigere Diagnostik als in der elektiven Situation, zudem geht die Prothesenimplantation nach Trauma mit einer höheren Komplikationsrate einher. Somit stellen sich folgende Fragen, die im vorliegenden Beitrag behandelt werden: Ist die notfallmäßige endoprothetische Versorgung nach Fraktur vertretbar? Wie sollte der Patient aufgeklärt werden? Stellt die endoprothetische Versorgung immer eine „Programmoperation“ dar und wann ist folglich der günstigste Operationszeitpunkt? Gilt der elektive Versorgungsansatz auch für die einfache mediale Schenkelhalsfraktur als klassische Indikation für die Endoprothesenversorgung nach Knochenbruch? Welches sind die operativen Besonderheiten der endoprothetischen Frakturversorgung und welcher Chirurg kann und sollte diesen Eingriff durchführen?AbstractThe indication for arthroplasty following trauma is generally established on the basis of the severity and type of the fracture, as well as on patient age. Thus, the initial situation in terms of surgery, as a result of these conditions alone, is significantly worse than in the case of primary endoprosthetic treatment of degenerative joint disease. Surgical planning also requires a more sensitive and usually more intensive diagnostic workup than for elective surgery, in addition to which arthroplasty following trauma is associated with a higher complication rate. For this reason, the present article examines the following questions: Is emergency endoprosthetic treatment following fracture justifiable? How should the procedure be explained to the patient? Does endoprosthetic treatment always represent “programmed surgery” and, if so, when is the optimal time for surgery? Does elective treatment even for simple medial femoral neck fractures count as a classic indication for endoprosthetic treatment following bone fracture? What are the particular surgical features of endoprosthetic fracture treatment and which surgeon can and should perform this type of surgery?

Combination of a floating clavicle and a posterior shoulder dislocation: An "Unhappy Triad" of the shoulder girdle.

We present a case of a 31-year-old man who suffered from a floating clavicle in combination with a reverse Hill-Sachs lesion of his right shoulder girdle after a bicycle accident. Operative treatment was performed using minimal-invasive and arthroscopically assisted techniques. We strongly recommend an early CT scan with later 3-dimensional reconstruction to detect and fully understand these complex injuries.

Impact of posttraumatic steps on the intra-articular pressure of the lateral tibial plateau after fracture reconstruction: A biomechanical human cadaver study

Aims and Objectives: The aim of reconstructing a tibial head fracture is the anatomical reconstruction. Which deviations from the anatomical position are tolerable and which misalignments could be treated conservatively, is currently not investigated. It is known that after tibial plateau fractures up to 7.3% of even treated patients develop a posttraumatic osteoarthritis requiring a prosthesis after 10 years. A rate of osteoarthritis after 5 1/2 years up to 40% is known after tibial head fractures. The aim of this study is to investigate the effects of the reduction on the intra-articular pressure distribution within the lateral tibial plateau in various degrees of flexion. Materials and Methods: In a human lateral tibial plateau fracture model (AO 41 B1, n = 8), the intra-articular pressure distribution was measured depending on misalignment after reposition (0-8 mm step in 1.0 mm steps) in various angles of flexion (0°, 15, 30°, 60°, 90°). Preserving the relevant ligamental structures, the soft tissues was removed and the knees wer embedded in PMMA cement (Technovit 3400, Heraeus). A standardized osteotomy, dividing the lateral articular surface in the middle of the primary-load zone has been performed. The lateral fragment was fixed by a self-constructed sled with an angular-stable plate (LCP TomoFix, Fa. Synthes) and moved in 1 mm steps from the anatomical position distal. The intra-articular pressure distribution was measured by pressure sensors (S2015 Double kneepad sensor, Fa. Novel) under axial compression on a servo-hydraulic testing machine (Instron 8874, Fa. Instron). Taking the mean of the averaged pressure distribution in the medial and lateral plateau, data was measured for 20 sec with a reading rate of 10 frames per second. Results: Increasing the misalignment-step, there is an increasing mean pressure in both plateaus in every angle of flexion. For example at 90° of flexion relative growth in pressure (means) in 1 mm increments steps: In the lateral plateau -5.6%; -2.1%; + 9.3%; + 11.8%; + 13.3%; + 15.9%; + 20.6%; + 23%. In the medial plateau, the pressure change is as follows: + 4.8%; + 8.0%; + 8.3%; + 8.8%; + 9.0%; + 9.3%; + 9.4%; + 9.5%. The data is similar in the other investigated degrees of flexion. The turning point of the pressure increase is lateral always at the 1-2 mm step. Conclusion: Small steps of only 2 mm lead to a significant increase in pressure - initially in the intact and later also in the fractured plateau. Referring to these findings, the indication for primary operative or conservative care and revision operations should be made. Intraoperative reposition should be performed as precise as possible - preferably controlled f.e. arthroscopically. The influence of the menisci on the pressure distribution is seen in the lateral plateau as it compensates the loss of area in smaller joint-steps. This mechanism will be content of further studies.