Orthopedics Hyperguide Review | Dr Hutaif General Ortho -...

The use of antibiotiCbone cement plus systemiCantibiotics is the most effective strategy in reducing deep infection. This is followed by the use of systemiCantibiotics alone, antibiotiCbone cement alone, and no antibiotics

Malchau and colleagues also performed Poisson modeling, assessing the risk of deep infection in revision surgery using different types of bone cement. Using Sulfix bone cement (Sulzer, Winterhur, Switzerland) as the numerator, the investigators assessed Simplex (Stryker Howmedica Osteonics, Allentown, NJ), CMW (Johnson & Johnson DePuy, Warsaw, Ind), Palacos (Merck/Biomet, Warsaw, Ind), and Palacos gentamicin (Merck/Biomet) bone cements. They developed a risk ratio for revision using any of these bone cements. Palacos gentamicin bone cement was associated with the lowest risk ratio for revision

The catastrophiCfailure of the precoat stem was due to proximal debonding associated with laser etching of the identifying numbers and letters on the stem of the prosthesis. Virtually all reported stem failures occurred in left hips because the laser etching caused a local stress concentration effect on the higher stress anterior surface

Type IVCinjuries include distal phalanx base fractures involving more than 50% of the articular surface. Most surgeons feel that accurate reduction is mandatory to prevent joint deformity, secondary arthritis, and stiffness

Patients may present with severe knee pain after a mild traumatiCevent. Patients may have the inability to extend the knee or walk. Laxity in flexion (flexion instability) can result in dislocation of the femorotibial articulation. The cam of the femoral component rides up and over the top of the post of the tibial polyethylene insert. The dislocation is usually the result of a traumatiCepisode.
Flexion instability occurs in about 1% to 2% of knee replacements when the knee is not properly balanced following a replacement. The extension and flexion gap must be equal. When balancing a knee, especially one that is tight in extension, the surgeon may choose to place a smaller tibial polyethylene component to achieve full extension with resulting instability of the knee in flexion because the knee flexion gap is larger than the polyethylene insert.
Treatment of flexion instability in posterior stabilized knee replacements can be nonoperative with casting or bracing initially. Two- thirds of patients can be managed successfully nonoperatively. If symptoms persist, revision to a larger polyethylene component can be very effective. If the knee remains unstable, revision to a more constrained prosthesis may be necessary

This is a common problem. Selection of a smaller polyethylene spacer results in a correction of the flexion contracture but also results in flexion instability as the flexion gap will be larger than the extension gap. First, surgeons should remove any posterior osteophytes from the distal femur. Second, the posterior capsule should be incised. If both of these maneuvers fail to correct the contracture, the surgeon should remove additional bone from the distal femur. The joint line may be raised up to 8 mm when performing posterior stabilized arthroplasties without compromising the result

These are important concepts when balancing the knee following total knee replacement.
The distal femoral cut only effects the extension gap.
The proximal tibia cut effects the flexion and extension gaps. The posterior femoral condyle cut effects the flexion only.
Attention to these principles is very important to prevent both contractures and flexion instability. Correct Answer: The distal femoral cut only effects the extension gap.

Flexion instability is common following revision total knee replacement. The following principles are important:
Undersizing the femoral component is common. This occurs secondary to the posterior femoral condyle bone loss.
Anterior translation of the femoral component increases the flexion gap. The use of posterior femoral condyle augments or an offset stem can solve this problem.
Distal femoral augments that are too thick will narrow the extension gap. One should set the joint line approximately 25 mm to 30 mm below the epicondylar axis.
Excessive size of the patellar component will restrict knee flexion, however, it will not change the flexion and extension gaps. Correct Answer: There is excessive thickness of the distal femoral augmentation blocks.

The noncircumferentially coated titanium alloy patch-porous coated straight Harris-Galante stem was associated with significant osteolysis, thigh pain, subsidence, and endosteal erosion. The patched porous coating is believed to allow ingress of joint fluid and wear debris into the endosteal canal, increasing the effective joint space

The size of the hole must not exceed 30% of the diameter of the shaft. Holes should not be placed any closer than two hole diameters apart, and they should be located in the anterolateral surface of the femur to decrease the stress riser

The gold standard for the diagnosis of avascular necrosis is magnetiCresonance imaging. Changes can be seen earliest with this technique before there are changes on routine roentgenogram and even before a patient is symptomatic

There is a lower incidence of infection reported in ceramic-ceramiCtotal hip replacements by the Swedish Hip Registry. This may
be related to the fact that bacteria typically adhere more strongly to polyethylene than cement, suggesting that both early and late infection may be lower for alumina than polyethylene total hip replacement

The first step toward osteoarthritis of the dysplastiChip is fatiguing of the labrum under normal stress. Klaue et al described the different pathomorphologies from a torn labrum to ganglion formation, which has been attributed to acetabular rim syndrome

The common iliaCartery divides at the L5-S1 vertebral disk. The anterior division, the external iliaCartery, continues distally to become the common femoral artery, whereas the posterior division becomes the internal iliaCartery. The internal iliaCartery branches again into a posterior division, which gives rise to the superior gluteal artery, and an anterior division, which gives off the obturator artery before dividing into the inferior gluteal artery and internal pudendal artery

The external iliaCartery and vein are immobile and lie close to the pelvis, and thus are at high risk for injury in THA. The external iliaCvein lies within 7 mm of the anterior column of the pelvis at the anterior inferior iliaCspine and within 4 mm at the acetabula dome. The external iliaCartery is at less risk due to its thicker intima and increased distance from the bone. The external iliaCartery lies within 10 mm of the bone at the anterior inferior iliaCspine and within 7 mm at the acetabular dome. The common femoral artery lies anterior and medial to the hip capsule. Only the iliopsoas lies between the vessel and capsule at this point. The femoral vein lies medial to the artery and is not likely to be injured. The obturator vessels are also at risk, lying fixed within 1 mm of the bony surface at the quadrilateral surface, with their only protection being the interposition of the obturator internus muscle

The primary nerves of the region are the sciatic, femoral, inferior and superior gluteal, and obturator. The most common nerve injury during THA is to the peroneal division of the sciatiCnerve, followed by superior gluteal, obturator, and femoral nerves. Injury to these structures can lead to loss of function and poor outcomes

The acetabular quadrant system described by Wasielewski and colleagues is useful for determining the location of planned acetabular screw fixation in THA to avoid neurovascular complications. The quadrants are formed by drawing a line from the anterior-superior iliaCspine through the center of the acetabulum and bisecting that line at the center of the acetabulum to form four equal quadrants. The line from the anterior-superior iliaCspine to the center of the acetabulum serves as the dividing line between anterior and posterior, and the bisecting line as the division between superior and inferior.
In cadaver studies, the posterior-superior and posterior-inferior quadrants were shown to have the thickest bone and best potential for obtaining secure fixation with the least risk for injury to vessels. The anterior-superior quadrant (the quadrant of death) and the anterior-inferior quadrant were shown to be the most dangerous quadrants for fixation due to the thin bone and close proximity of the vessels to bone in that region

The posterior approach to the acetabulum is the least technically demanding approach for total hip arthroplasty (THA) and offers good visualization of the acetabulum, especially of the posterior wall. The posterior approach is the most commonly used approach for THA in the United States. Patients are placed in the lateral position. The approach involves splitting of the gluteus maximus in line with its fibers and no internervous plane is present. The sciatiCnerve is protected by the short external rotators after they are detached from their insertions on the femur and reflected medially

The ilioinguinal approach provides improved visualization of the pelviCinner surface and anterior column and medial wall of the acetabulum. The patient is placed supine or in a lazy lateral decubitus position. The principle of this approach is to dissect closely along the inner wall of the pelvis and lift each muscular and neurovascular structure off of the bone. Three windows are present in this approach, each providing access to different structures. The first window allows access to the anterior sacroiliaCjoint, internal iliaCfossa, and upper anterior column

If extensive osteolysis is suspected, computed tomography is recommended because plain radiographs underestimate the extent of lysis. Helical computed tomography with metal artifact minimization is the most sensitive method for identifying and quantifying the extent of lysis

A previous review of vascular injuries sustained during THA revealed the most common etiology of vascular injury as thromboemboliCphenomena, followed by laceration, pseudoaneurysm, and arteriovenous fistula

Damage to the femoral vessels is most commonly due to aberrant retractor placement. Care should be taken to ensure that the retractor tip is placed directly on bone, and that the iliopsoas is not interposed between the retractor tip and bone. Extruded cement, acetabular cup migration, and capsule dissection have also been implicated in damage to the femoral vessels

Following primary THA, the incidence of nerve palsy is reported to be approximately 1.3%, but may be as high as 5.2% for primary THA performed for developmental dysplasia or dislocation. For revision surgery, the incidence may be as high as
7.60%

This radiograph presents a Brooker class IV heterotopiCossification in a 79-year-old woman after revision of a monopolar hemiarthroplasty to a press-fit, porous-coated acetabular component and a cemented femoral stem. The patient sustained a cerebrovascular accident 12 weeks before surgery. She had no other risk factors for heterotopiCossification formation after total hip arthroplasty. Other risk factors for heterotopiCossification include previous surgery, men with hypertrophiCosteoarthritis, traumatiCbrain injury, spinal hyperostosis, and posttraumatiCarthritis

Osteomyelitis of the pubiCsymphysis is a rare condition, accounting for less than 1% of all acute hematogenous osteomyelitis cases. The condition is well described in elderly patients following urologic, gynecologic, and pelviCprocedures. Osteomyelitis of the pubiCsymphysis has also been reported in intravenous drug abusers, after cardiaCcatheterization, and can occur spontaneously in athletes and children

Osteomyelitis of the pubiCsymphysis is a rare condition, occurring in 2% to 11% of all patients with osteomyelitis of the pelvis. The osteitis pubis is the least affected area. Signs and symptoms of osteomyelitis of the pubiCsymphysis include distal anterior pelviCpain, adductor and rectus muscle spasms, and a wide-based waddling gait. Fever, leukocytosis, elevated erythrocyte sedimentation rate, and positive blood cultures may also be present. Unilateral rarefaction and sclerosis with cystiCchanges may be seen on radiographs 10 to 14 days after symptoms begin. Radionucleotide scans, computed tomography, and magnetiCresonance imaging may aid in the diagnosis

The etiology of extensor mechanism disruption after TKA is unknown. Researchers suggest that disruption of the vascular supply to the patella and patellar mechanism during the exposure may cause weakening of the patella and extensor mechanism. In addition, the frequency of extensor mechanism disruption has been reportedly increased in patients who have a preoperative limited range of motion or difficult surgical exposure

Female athletes are two to eight times more likely than men to sustain an anterior cruciate ligament injury when playing sports such as soccer, basketball, and volleyball. The exact etiology of gender-based injuries is unclear. Various intrinsiCfactors (intercondylar notch width, ligament size, quadriceps angle, joint laxity, hormonal effects) and extrinsiCfactors (muscular strength/weakness, fitness level, hamstring:quadriceps ratio) have been proposed as contributing factors. A strong hamstring actually protects the anterior cruciate ligament and is a preventative measure

Medical consequences of time issues relevant to hip fractures have been examined by several authors. Operation within the first day of injury is superior and provides better results than delaying the procedure. However, the economiCconsequences of such a delay have not been examined

Baker's or popliteal cyst, described first by Adams and later by Baker, is a distended bursa originating posterior to the medial head of the gastrocnemius muscle or semimembranous tendon and generally presents with posterior knee pain and a palpable mass. This case is unusual in that the dissection was proximal, unlike the typical distal progression of the popliteal cyst

Over the past two decades, a continuous shift toward outcome assessment in medicine has occurred. Publications previously devoted to technical details and surgical technique have started analyzing and measuring the impact and longevity of medical procedures on patients' quality-of-life and have compared the cost-effectiveness of different procedures

In the study design, it is paramount that a universal, well-defined endpoint is chosen. In the well-established Scandinavian Hip Registries, this endpoint is revision total hip arthroplasty. Whether this endpoint is sensitive enough is debatable. For more in- depth studies, several other endpoints, such as pain or postoperative functional level, may also be used

For the implanted prosthesis, manufacturer, name, material, and catalogue numbers are essential for precise future identification. The role of the catalogue numbers cannot be underestimated as successive generations of implants were put on the market with the same brand name (eg, Charnley hip). Without recording the catalogue numbers, it is impossible to determine what generation of implant is being compared to another

The main advantage of multicenter studies - although they are time-consuming, expensive, and often frustrating - is obtaining large numbers of patients in a relatively short time. This is important when examining statistical differences between varying results

Because of the safety concerns, immunogenicity issues, and production complications associated with viral vectors, nonviral delivery systems were developed by complexing of genes (DNA) to various chemical formulations. Nonviral delivery systems stabilize DNA and increase its uptake and include plasmids, peptides, cationiCliposomes, DNA-ligand complexes (recognize
specifiCcell-surface receptors, leading to receptor-mediated uptake), and gene gun (particles of gold coated with DNA, forced into the cells with high velocity bombardment). However, nonviral vector efficiency is lower than viral vectors

A retroviral vector derived from the Moloney murine leukemia retrovirus is among the best-developed viral vectors. Other viral vectors include adenovirus, adeno-associated virus, and herpes simplex virus. Novel vector systems based on lentivirus, which is a type of retrovirus that includes human immunodeficiency virus, are being developed

Novel approaches to treating genetiCdiseases involve gene repair or replacement rather than gene supplementation. One such approach is based on the principle of homologous recombination (replacement of a defective gene by a normal gene)

Adenoviral vectors can cause inflammatory reaction due to immune activation, an event linked to the first death related to gene therapy. This occurred in September 1999 at the University of Pennsylvania in a clinical trial in which an 18-year-old patient received infusion of more than a trillion adenoviral vectors directed to his liver, which triggered a systemiCinflammatory response that became uncontrollable, leading to organ failure and death. Newer-generation gutted or gutless adenovirus vectors are nonimmunogenic

Two basiCstrategies exist for gene delivery. Direct, or in vivo, gene therapy involves direct introduction of vectors into the body. Indirect, or ex vivo, gene therapy involves removal of target cells from the body, vector introduction by incubation of the cells in vitro, and reimplantation. The in vivo system is less invasive

Gene therapy has been suggested as a means of delivering sustained therapeutiClevels of anti-arthritis gene products to diseased joints. Local gene delivery to the synovial tissue is the approach of choice for osteoarthritis and other conditions affecting a few joints. Gene therapy is less suited to address the extra-articular components of systemiCconditions, such as rheumatoid arthritis.
The gene that has been studied in greatest detail encodes the human IL-1 receptor antagonist. Correct Answer: IL-1 receptor antagonist

Identification of LMP-1, a novel intracellular protein, is a step forward in osteoinductive proteins. Unlike bone morphogenetiCprotein, which is a secreted protein that binds to cell-surface receptor to initiate a response, LMP-1 is an intracellular signaling molecule. Boden and colleagues transfected bone marrow cells from rats ex vivo with LMP-1 gene using DNA plasmid vector and used them during posterior thoraciCand lumbar spinal fusion in rats

Various cytokines and cytokine antagonists hold promise as new therapeutiCagents for osteoporosis. Baltzer and colleagues showed that intramedullary injection of Ad-IL-1Ra gene in a murine ovariectomy model strongly reduced the loss of bone mass. Using a similar model, Bolon and associates studied the effect of adenovirus-mediated transfer of osteoprotegerin, which showed more bone volume with reduced osteoclast numbers in axial and appendicular bones after 4 weeks compared with sham-operated mice

In vivo gene delivery involves the direct injection of vectors containing the genes into the body with the expectation that they will reach and transduce the target cell. Ex vivo gene delivery is a process whereby the target cells are removed from the body, genetically altered in vitro, and reimplanted into the body

Intervertebral disk degeneration has been associated with a progressive decrease in proteoglycan content of nucleus pulposus. The potential application of gene therapy for prevention of disk degeneration is to increase or maintain the proteoglycan content of nucleus pulposus. Thompson and colleagues reported that addition of TGF-Ã1 to canine disk tissue in culture stimulated in vitro proteoglycan synthesis

Arthroscopy facilitates a thorough assessment and treatment of a rotator cuff tear by approaching the shoulder from multiple angles. It preserves the deltoid attachment to the acromion and postoperative rehabilitation is potentially accelerated if the deltoid does not need to be protected. Arthroscopy achieves a better early range of motion than other repair methods; however, it requires a longer operative time

ArthroscopiCrepair techniques generally require the use of suture anchors and limit some suture configuration options in the tendon. Complete arthroscopiCrepair is technically difficult, requires significantly greater and more complex instrumentation, and has a potentially longer operative time. However, it decreases postoperative pain