Purpose: Intraarticular use of anaesthetic agents is common for postoperative pain relief after arthroscopic knee surgery. In this study, we have evaluated and compared the effects of Bupivacaine, Levobupivacaine and Tramadol both invivo and invitro experimental rat models on articular cartilage and chondrocytes.

Materials and Methods: Invivo Experiment: 1. Injections: Thirty mature Sprague-Dawley rats weighing 230 – 300 g were randomized into 3 groups. Bupivacaine (Group 1), Levobupivacaine (Group 2) and Tramadol (Group 3) were injected into the right knee joints and physiological 0.9% saline into the left. 2. Histopathologic Analysis: The specimens were fixed, decalcified and stained with Hematoxylen and Eosin (H& E) and Toluidin Blue. All slides were examined by the same pathologist, who was blinded to the injectate used in each joint. All samples were evaluated histopathologically according to the recommendation of International Cartilage Repair Society’s osteoarthritis and cartilage histopathology grading and staging system. Invitro Experiment: Articular cartilage cells of the rats were cultured and seeded. Cartilage cell seeded samples (104 cells/mL) were incubated in three different anesthetic agents (0,5%); Bupivacaine, Levobupivacaine, and Tramadol respectively. Cell Titer 96TM Nonradioactivity Cell Proliferation (MTS) assay was used to determine the cell density on the samples.

Results:

Invivo: There were pathologic changes like cartilage hypertrophy, active chronic inflammation with abscess formation, cellular proliferation, focal vertical fissures and focal discontunity on cartilage matrix at superficial zone in all three groups on the drug injected sides. Although those histopathologic findings were not found statistically significant when compared the OARSI grade, OA stage and OA score with the control groups (p> 0.05), statistically significant higher OARSI grade, OA stage and OA scores were detected when compared the Levobupivacaine injected group after 10 days with the Levobupivacaine injected group after 48 hours (p< 0.01 [ p=0.008]).

Conclusion: No report has been appointed comparing the effects of the mentioned three drugs both invivo and invitro. Although chondrotoxicity of Bupivacaine was less harmful than Levobupivacaine and Tramadol, these findings suggest that local anesthetics negatively affect articular cartilage and chondrocytes. Given that chondrocyte loss has been implicated in the development of chondrosis and osteoarthritis, orthopaedic surgeons should be careful in their preference for pain control with intraarticular drug injections after arthroscopic procedures.

Purpose: Presently, tension band figure-of-eight fixation of olecranon fractures is usually performed with stainless steel wire. A polyethylene cable cerclage has been proposed as an alternative to lessen the complications associated with wire. This study compared the stability of tension band constructs for olecranon fracture fixation using a polyethylene cable cerclage or a stainless steel wire cerclage.

Methods: Ten matched pairs of fresh-frozen cadaveric elbows, without radiographic abnormality, were selected for the study. In each specimen, a transverse fracture was created by an osteotomy at the middle of the sigmoid notch of the olecranon. One elbow of each pair was randomized for tension band fixation with a figure-of-eight construct while the other was fixed by tension banding with a loop cerclage. Two different materials, stainless steel wire and isoelastic polyethylene cable, were randomly selected to create the cerclage constructs in each elbow. The triceps tendon was controlled and cyclic loads were applied to the dorsal cortex of the ulna 8 cm distal to the fracture site to create a bending moment. The elbow was initially preconditioned at 45 N for 100 cycles, followed by four periods of 300 cycles each, from 45 N to 120 N in 25 N increments. Dynamic and static fracture gap for the different configurations and materials were recorded.

Results: No difference in static gap was found between the metal figure-of-eight, cable figure-of-eight and cable loop constructs (p> 0.05). The metal loop was found to have significantly greater gap (p=0.0013) than the other 3 constructs. No difference was observed in dynamic gap at the peak loads for any of the constructs (p=0.3379).

Conclusion: This study demonstrated that the biomechanical performance of tension band fixation in an olecranon fracture model using a polyethylene cable in either figure-of-eight or loop construct is similar to that of the stainless steel wire figure-of-eight construct and should be considered as an option to the traditional stainless steel wire. This type of soft and tissue tolerant fixation may lessen the known clinical complications of wire fixation while providing equivalent stability under physiologic loads which would permit early rehabilitation.

A conventional implant/bone construct typically involves a plate fixed to a fracture bone via set of screws aligned vertically to the plate/bone interface. In this study new configurations of plate/bone constructs with varied screw angulations were tested. The conventional screw configurations a parallel set of screws aligned vertical to interface were tested against two new configurations, called the divergent configuration and the convergent configuration. A total of four construct systems were prepared for tests. The samples used in the experiments are listed. Sample A, named conventional construct, used a set of parallel screws drilled vertical to the interface plane. Sample B, named convergent construct, used screw holes drilled such that their axes converged. Samples C and D, named divergent construct, used screw holes with diverging axes. The difference between Samples C and D is in the angle of alignment between their screw axes and the normal to the interfacial plane, the former drilled at 150 and the latter at 300. The load displacement curves for the four samples are shown. The failure loads, along with the mode of failure for each sample are read from the load-displacement curves. At a first glance, it is observed that the sample with highest pullout strength in terms of failure load is the conventional construct (A). This is followed by the divergent constructs (C and D), and the sample with the lowest strength is the convergent construct. It takes a more careful investigation, however, to note that similar results will not apply when one takes the average pullout stiffness as a criterion. Here, we define the average pullout stiffness of the structure as It is immediately noticed that samples producing the highest stiffness are those prepared as divergent constructs (C and D), followed by the convergent construct (B), and finally, Sample A produced the lowest stiffness. Also note that the initial portion of the load-displacement curve for Sample D (300 screws) is highly nonlinear, although the curve then assumes a linear shape. The stiffness obtained in the linear region of Sample D, and that of Sample C are quite close in comparison.

This initial deviation in the curve of 300 divergent screws may be explained by a self-aligning motion of the screws as the load is applied, during which the angle of alignment tends to decrease towards a smaller angle. As the angle gets closer to that of Sample C and the curve becomes linear, the stiffness produced by Sample D, approaches to that of Sample C.

As a result, we have found the divergent constructs to be a promising alternative to the conventional set of screws, used in treating fracture involving bones with osteoporosis. Moreover, research needs to be focused on determination of an optimal angle of alignment, the number of screws to be used and the optimal distance between each screw for the divergent construct.