In order to detect and femur during knee flexion and extension cheap hoodia 400 mg otc herbs used for pain, and understand deformities of the lower extremity purchase 400 mg hoodia planetary herbals quality, while it is obviously important no clinically use- it is important to establish the limits and param- ful tracking measurement systems exist and the eters of normal alignment based on average val- loading characteristics of the patellofemoral ues for the general population. The relationship of the patella to the femur Frontal Plane Alignment (patellar malalignment) must be viewed in all Frontal plane alignment is best determined three planes (Table 11. In the coronal plane, using longstanding AP radiographs including one can measure Q-angle and patellar spin. To determine the the sagittal plane one can measure patellar flex- mechanical axis a line is drawn from the center ion and height; in the horizontal plane one can of the femoral head to the center of the ankle measure patellar tilt or shift. Typically, normal alignment shift and mini-tilt may both be manifestations of is defined as the mechanical axis passing just medial to the center of the knee. It is a common mistake to consider alignment ment refers to the mechanical axis passing lat- as referring only to the position of the patella on eral to the center of the knee while varus refers the femoral trochlea. Alignment refers to the to the mechanical axis passing medial to the changing relationship of all the bones of the center of the knee. Mechanical alignment is the sum total femoral head to center of knee to center of talus) of the bony architecture of the entire lower and the anatomical tibiofemoral angle (line extremity from sacrum (center of gravity) to the down center of femoral shaft and line down cen- foot (ground). The position and orientation of ter of tibial shaft). The mechanical tibiofemoral patellofemoral joint to the weight-bearing line angle is the angle between the mechanical axis of determines the direction and magnitude of the femur and the tibia. Classification of patellar malalignment Frontal plane Sagittal plane Horizontal Plane Internal rotation External rotation Flexion Extension Medial tilt Lateral tilt (spun) (spun) High Q-angle Low Q-angle Alta Baja Medial shift Lateral shift (translation) (translation) 188 Etiopathogenic Bases and Therapeutic Implications Table 11. Classification of skeletal malalignment Frontal plane Sagittal plane Horizontal plane Location Location Location Varus Femur Prominent trochlea Femur Inward-pointing Femur (internal torsion) Tibia knee Ligaments Tibia (external torsion) Subtalar joint complex (hyperpronation) Valgus Femur Shallow trochlea Femur Outward-pointing Femur (external torsion) Tibia knee Ligaments Tibia (internal torsion) Subtalar joint complex Aplasic tuberosity Tibia Increased TT-TG Tibia > 20 mm Decreased TT-TG is the angle between the femur shaft and tibia Rotational (Horizontal or Transverse) shaft and is usually 5. Different investi- Plane Alignment gators found no difference between males and Rotational plane alignment can be determined females in these angles. Common measurements are the torsion of the femur, torsion of the tibia, version or the relationship of the distal femur and prox- imal tibia, and the relationship between the femur and the tibial tuberosity (TT-TG). Bone Torsion Femoral torsion is defined as the angle formed between the axis of the femoral neck and distal femur and is measured in degrees. To assess femoral torsion with CT scan a line from the center point of the femoral head to the center point of the base of the femoral neck is created. This second point is more easily selected by locating the center of the femoral shaft at the level of the base of the neck where the shaft becomes round. Based on the classic tabletop method, the condylar axis is defined as the line between the two most posterior aspects of the femoral condyles. Alternatively a line connect- ing the epicondyles can be used. Then, the angle formed by the intersection of these two tangents is measured (Figure 11. For assessment of tibial torsion a line is drawn across the center of the tibial plateau. As this line is not easy to locate, some authors use the tangent formed by the posterior cortical margin of the tibial plateau. The femoral epicondylar axis might also be selected as it is easier to locate and would appear to be valid because it is the relationship of the knee joint axis to the ankle joint axis that is of concern. Whole limb standing radiograph with mechanical axis ing the center point of the medial malleolus with added showing varus. Skeletal Malalignment and Anterior Knee Pain 189 Figure 11. CT rotational study shows 43° of femoral anteversion. Line 1 represents the proximal femoral axis; line 2 is the distal femoral axis (tan- gent to the posterior condyles). The angle formed by the intersection of axis (SD 8°). His values generally agree with those these two lines is measured to determine the tib- reviewed in the literature that he tabulated. Conversely, lateral tibial torsion aver- torsion determinations in normal individuals aged 24° with a significant difference between using CT scan. The authors measured torsion in males and females at 21° (SD 5°) versus 27° (SD 505 femurs and 504 tibia and found femoral 11°). Furthermore, even greater differences were anteversion of 24.
For many women buy 400mg hoodia free shipping herbals books, cellulite marks the end of the idyllic youthful body and the onset of the aging discount hoodia 400 mg fast delivery quality herbals products pvt ltd, declining female shape. Certainly, there must be something that technologic medical science can offer. Even in the 1960s, cellulite treatments abounded with the vibrating belt machines designed to ﬁrm the buttock and thighs while minimizing cellulite. At the time of this writing, there are many creams, devices, and proce- dures that attempt to deal with the ubiquitous problem of cellulite, but an organized scientiﬁc treatise is lacking. This text is the ﬁrst serious evaluation of the etiology and treatment of cellulite. The editors have assembled an international panel of cellulite researchers and clinicians to share their combined knowledge on the subject. The book is nicely organized with an introduction into the social impact of cellulite, followed by a characterization of the problem through visual and noninvasive techniques, with a major focus on the various treatment modalities. The editors thus provide a full critical evaluation of how each of these treatments impacts the appearance of cellulite. Most dermatologists would agree that not a day goes by in clinical practice without a patient asking about cellulite treatments. To date, it has been difﬁcult to ﬁnd any reputable reference source on the subject. This text is a large step forward in characterizing the etiol- ogy of cellulite and evaluating worthwhile treatment approaches. The editors and their v vi & FOREWORD authors should be congratulated for tackling a complex subject and organizing a text to highlight and discuss the controversies. This book is an illuminating treatise on the cloudy topic of cellulite. Department of Dermatology Wake Forest University School of Medicine Winston-Salem, North Carolina, U. Preface Beauty has been extolled and made a cult object in all cultures and civilizations, whatever their geographic distribution, ethnic origin, or religion. In ancient Egypt, beauty was associated with a sacred nature and personiﬁed by Queen Nefertiti, a woman who had high brows, wide and well-delineated eyes, rich lips, a digniﬁed countenance, and an upright bearing, the very image of subtle energy; the ancient Egyptians regarded beauty closely akin to ‘‘holiness. The Greek aesthetic ideal was characterized by ‘‘perfect proportions’’ in the sense of the geometric relationships deﬁning body harmony. Aphrodite, the goddess of beauty, was also worshipped as the goddess of love. Among the Etruscans, the Venus of Melos repre- sented beauty and harmony; this has remained intact and unpolluted throughout subse- quent civilizations. PREFACE & ix During the Renaissance, the tall ﬁgures of Aphrodite and Venus, slim but muscular at the same time although somewhat androgynous, became impressive and important, as is evident in the works of Rembrandt and Rubens. The beauty of women was embodied in ﬁgures with abundant localized adiposity, though not obese: the faces were round and blissful and expressed a superb femininity and kindness that conveyed the idea of motherhood and protection. After the French Revolution, the standard representation of the woman took a new turn. The feminine body started to express activity, labor, functionality, precision, and har- mony, losing some traits of Renaissance femininity. In the new society established after the Revolution, women slowly acquired new roles, carried out new activities, and achieved an unprecedented independence. As time went by, women even started to smoke cigarettes and practice sports. There were no objections to this new role as long as the exaggeration and myths of a sculptured body—such as those characteristic of the 1960s—are avoided. They also draw our attention to the functionality and the cleansing process of the whole organism. Besides, it involves hardly controllable changes in the locomotor, digestive, and endocrine system. Last, but not least, it is a cause of dis- comfort and an ill-tolerated lack of aesthetics that drives the patient to accept any type of so-called therapeutic treatments in order to solve the problem. Too frequently such ‘‘treat- ments’’ have no scientiﬁc basis.
Polarization Testing—Current/Potential Response A standard electrochemical test used to evaluate the corrosion resistance of implant alloys is the polarization test generic 400 mg hoodia with visa herbals for horses. This test assesses the current/potential characteristics of the metal solution interface by varying the potential of the interface and measuring the resulting current purchase 400 mg hoodia visa herbs coins. Varying the potential across the metal–oxide–solution interface in a controlled fashion forces the oxida- tion and reduction reactions, which are at a dynamic equilibrium at the open circuit potential to deviate from equilibrium. For instance, for metals which do not form passivating films (not implant alloys), the current/potential relationship is represented with the Butler-Volmer equation: n bc n (6) icorr = io [exp − exp ba where icorr is the corrosion current at the applied potential is the overpotential (the potential difference between open circuit and the applied poten- tial) ba and bc are the Tafel constants io is the exchange current density. From these polarization tests, information characteristic of the corrosion currents and potentials can be obtained, as well as the nature of the electrochemical behavior when the potential of the interface is different from the resting OCP. The typical instrumentation used for polarization tests is a potentiostat. Polarization tests are performed by applying a potential (voltage) to a metal sample (working electrode) relative to a standardized reference electrode. A counterelectrode is used to complete the circuit and to provide a current sink so that the reference electrode is not affected by the current that flows. A typical curve for a polarization test of a passivating metal is shown schematically in Fig. There are four regions of this plot that are the result of different behavior of the electrode surface. At potentials positive of the equilibrium potential, the metal has a thermodynamic driving force for oxidation and is in the active region, i. A passive film has not formed to the extent that it can limit the rate of corrosion, although incomplete oxide film formation may be occurring. This continues until the potential is increased to a sufficiently more positive potential where the metal will spontaneously begin to form an oxide film on its surface. When this film fully covers the metal substrate, the metal is said to become passive, and the potential at which this occurs is known as the passivating potential, Epp. This kinetic barrier prevents further oxidation, and the current that flows drops dramatically. As long as the oxide layer remains intact on the surface, further increases in electrode potential will not significantly increase the current. However as the potential is increased further in the passive range there is an increase in the thickness of the oxide film. This process is known as anodization and can be used to thicken the oxide film. For titanium, the anodization rate has been reported to be in the range of 20 A/V˚. Figure 2 Schematic for a polarization test of a pure metal in water with no other electrochemical reactions taking place. The y axis represents the voltage of the metal surface relative to a standard electrode of some sort, and the x axis represents the log of the current produced by the corrosion. The areas of different corrosion behavior are indicated by the dotted lines. Below the equilibrium potential (Em) metal ions tend to come out of solution onto the metal surface. Between the equilibrium potential and the passivation potential (Epp) metal ion release from the surface is thermodynamically favorable, without inhibition by surface oxide formation. However, between the passivation potential and the breakdown potential (Eb) the surface of the metal is protected by the formation of an oxide layer (i. Above Eb the driving force for ionization overcomes the protective surface oxide, resulting in corrosion within the transpassive region. Once the potential is increased further to a value where physical limitations to oxide layer growth reduce its ability to kinetically limit the high thermodynamic driving force for oxidation, the corrosion currents can increase and the electrode is said to enter transpassive behavior. This transition potential is referred to as the breakdown potential, Eb.
Figure 7 Molecular structure of polymethylmathacrylate purchase hoodia 400mg amex quality herbals. BONE CEMENT Bone cement is presently made mostly of the nondegradable polymer polymethylmethacrylate (PMMA) (Fig buy hoodia 400mg mastercard herbs denver. Surgeons internally cement fractures and total joint prostheses with PMMA by an in situ polymerization reaction. Injection of the monomer mixture and photopolymerization allows for a less invasive surgical technique. The mechanical properties of PMMA are sufficient to bear the stress of in vivo loads. For example, it is difficult to control the temperature rise associ- ated with exothermic polymerization. Temperatures at the bone–cement interface often reach up to 90 C causing cell necrosis. In addition, PMMA cement often causes reduced blood flow irritation. Poly(Propylene-Furmarate) Networks To overcome the disadvantages of PMMA, researchers are developing polymers that can be polymerized in situ during surgery. Mikos and coworkers have synthesized degradable poly(pro- pylene-fumarate) networks for bone cement applications (Fig. In general, network poly- mers exhibit greater mechanical strength than their linear counterparts. Network 8 is formed by initiation with benzoyl peroxide. The polymer is mechanically weaker than PMMA [27,28]. However, by creating networks with higher crosslinking densities, higher strengths may be achieved. Also, the degradation products of this polymer 8 are nontoxic. In addition, the polymer has been shown to deliver bone growth–enhancing bioactive drugs to the fracture site upon degradation. Polyanhydride Networks Anseth and coworkers have reported polyanhydride networks that are formed by photoinitiation and are hydrolytically degraded (Fig. The polymer degrades by a surface erosion mechanism. Photoinitiation can also take place through tissue for an even less invasive surgical technique. By using a mixture of monomers, 9 and 10, controlled degradation times can be achieved ranging from 3 to 500 days. Also, by using a CQ/TEA initiating system, Anseth has achieved network thickness of approximately 3 cm. Histological studies have also shown that the monomers, 9 and 10, and polymer network 11 are biocompatible. By shuttering the light source used to polymerize, temperature at the bone–polymer interface has been controlled to 42 C. Finally, these networks have been shown to form on acceptable time scales, from 500 to 1500 s, depending on the intensity of the light used to initiate polymerization. Adosorbable Polymers for Orthopedic Repair 155 Figure 8 Synthesis of poly(propylene-fumarate) networks. CONCLUSIONS Linear and crosslinked networks, absorbable polymers, and copolymers have been studied for possible use in absorbable orthopedic hardware and cements. These materials have many advan- tages over current nondegrading technologies, including their ability to degrade at a controlled rate by a surface erosion mechanism. This allows researchers the opportunity to synthesize Figure 9 Synthesis of polyanhydride networks.