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

Intra-articular steroids change synovial fluid characteristics by increasing hyaluroniCacid concentration

The chance of an injection site irritation is 5.2% with a medial approach in a partially bent knee, 2.4% with a straight injection, and 1.5% with a direct lateral approach. There is also an increased chance of irritation with a direct patellar tendon injection

Indications for a high tibial osteotomy include age younger than 60 years, 10° to 15° varus deformity, 90° preoperative arCrange of motion, and flexion contracture less than 15°

Lateral compartment narrowing, lateral tibial subluxation of more than 1 cm, medial compartment bone loss of more than 3 mm, and ligament instability are contraindications to high tibial osteotomy

The incidence of primary lateral gonarthrosis in women is five times higher than in men, and the average age of patients is 55 to
60 years. The body habitus of women tend to align more weight on the lateral compartment when compared to men.Correct
Answer: Five times higher in women

Rheumatoid arthritis usually involves the lateral compartment because it is a bicompartmental disease. Although most patients with osteoarthritis have medial compartment arthritis, they still have a significant higher incidence of lateral arthritis than any other disease. The incidence of lateral compartment arthritis is lower in trauma, collagen vascular disease, or patients with neurologiCconditions like polio

Varus producing supracondylar femoral osteotomy is indicated for a valgus deformity less than 15°, valgus joint line tilt more than 10° in a patient with at least a 90° arCof motion. The procedure is also best indicated in stout, young patients who are involved in heavy labor jobs

Correcting the tibiofemoral angle between 4° to 6° transfers 80% of the weight to the medial angle

Patella infera is encountered 80% of the time after a high tibial osteotomy. Patella infera makes it difficult for a surgeon to visualize and dislocate the patella laterally, and it also makes for a difficult salvage for a total knee replacement

Primary TKA with respect to Knee Society scores and operative complications shows that a primary TKA group scored 88% good to excellent results compared to 63% for the post-HTO group

Subchondral drilling allows the blood supply to form clot-containing stem cells from which fibrocartilage forms. It is not indicated in patients with systemiCdisease like rheumatoid arthritis. It is ineffective for varus or valgus alignment or subchondral sclerosis

When performing a mosaicplasty for cartilage defects, the best results are obtained with defects less than 2 cm. The plugs should measure 2.5 mm in length. Mosaicplasty results for defects larger than 2 cm have not been as gratifying

Mobile-bearing TKR implants are designed to have two articulations, one between the femoral and tibial component and the other between the tibial component and base plate on the tibia

At 5 years, cemented all-polyethylene tibial components in total knee replacement have a loosening rate of 20%. A loosening rate of 20% is unacceptable, therefore, cemented all-polyethylene tibial components are no longer used in total knee replacements. New all poly tibial components are presently being investigated, but not for general use presently

Most authors recommend a 7-cm distance between skin incisions. If the distance between the incisions is less than 7 cm, then the chance of skin slough increases

The medial parapatellar skin incision limits exposure of the lateral compartment and interferes with the blood supply of the lateral skin flap

All of the answers are associated with the subvastus arthrotomy. A subvastus arthrotomy is a particularly difficult approach in obtaining visualization in an obese patient

The quadriceps snip technique entails dividing the tendon proximally in an oblique fashion to permit extended exposure.Correct
Answer: The quadriceps snip technique permits extended exposure.

Valgus in the tibia shaft may be up to 70%, and intramedullary rods cannot be fully placed into the tibia. Extramedullary techniques are recommended

The tibial cut is perpendicular to the tibial axis, the femoral cut is made in 4° to 6° valgus, and the knee aligned in 4° to 6° of valgus provided the ligaments are balanced

To have a satisfactory alignment one should have a valgus aligned knee, not a neutral aligned knee. Range of motion should be
0° to 125° with midline tracking patella. The collateral ligament should be balanced at full extension an 90°

The measured resection technique is a philosophy that removes the exact amount of bone necessary to fit in the prosthetiCdevice for the femur and tibia, and does not detail ligament balancing. The flexion-extension gap technique incorporates ligament balancing with the bony cuts that give equal flexion and extension gaps

By removing more bone from the femur in extension and using a higher polyethylene component, the flexion and extension gaps can be equalized. If this does not correct the problem, then one should proceed to a posterior stabilized prosthesis

If the flexion gap is smaller than the extension gap, the knee should be balanced by removing more posterior bone from the femur or downsizing the femoral component

Internal rotation of either the femoral or tibial component may lead to patellar dislocation. External rotation of the femoral or tibial component does not usually lead to dislocation, and increased size of the femoral or tibial component will not predispose to patella dislocation

Nausea, hypotension, respiratory depression, and peroneal nerve palsy are associated with epidural analgesia. Be aware of an epidural bleed secondary to anticoagulation efforts for deep venous thrombosis prophylaxis

This painful clunking sensation from 60° to 30° is caused by a fibrous nodule under the distal quadriceps tendon. Contributing factors include a large patellar component with proximal overhang and an abrupt change in the radius of curvature of the femoral component that irritates the quadriceps tendon

Metal-backed patella components minimize deformity of the overlying polyethylene and do not increase deformity. These components enable an even distribution of load transmissions and reduce the polyethylene thickness at the periphery of the implant. Metal-backed patella components also allow for cementless fixation of the patellae component

The polyethylene wear exposing the metal to wear against the femoral component is the ultimate result of all of the above failure modes except increased patella dislocation

The incidence of patella component loosening is less than 2%. Factors predisposing to loosening include cementation into deficient bone, component malposition, patellar subluxation or fracture, patellar avascular necrosis, asymmetriCpatellar bone resection, and loosening of other components. Treatment options include observation, component revision, patellectomy or component removal, and patellar arthroplasty if bone stock is sufficient

Large, central patellar-fixation lugs remove a significant amount of bone, which contributes to patellar fractures. Three small peripheral-fixation lugs are preferred in most designs

Trauma, failure to perform a lateral release, and prosthetiCdesign are associated with patellofemoral instability, but the majority
of patellofemoral instability cases are secondary to errors in surgical judgement and technique

The femoral component size, rotation, position, and alignment influence patellofemoral mechanics. For instance, an oversized femoral component leads to "overstuffing" that results in decreased flexion of the knee. Excessive flexion gap does not influence patellofemoral mechanics

The tibial component must be positioned in external rotation and lateralized when possible. Internal rotation or medialization predispose to patellar subluxation

The risk factors associated with fracture of the distal femur proximal to TKR are anterior femoral notching (especially if more than
3 mm in depth), rheumatoid arthritis, steroid use, osteopenia, revision arthroplasty, neuromuscular disorders, stiff knee, or poor flexion of the TKR

Severe valgus deformity, flexion contracture, and epidural anesthesia are risk factors associated with peroneal nerve palsy following TKR. Previous lumbar laminectomy and previous valgus osteotomy of the tibia also increase a patientâs chance of peroneal nerve palsy

Poor preoperative range of motion is the main cause of stiffness after TKR

The femoral component can be malaligned in one of eight different directions

Inserts thinner than 6 mm are associated with easy failure and osteolysis, caused by fracture and wear of the polyethylene

Usually, reflex sympathetiCdystrophy is a diagnosis of exclusion characterized by a syndrome of pain out of proportion to the clinical findings; a bone scan may demonstrate increased uptake in the affected area

These symptoms, in addition to pain out of proportion to clinical findings, characterize a slow postoperative course. Poor function after total knee replacement is usually secondary to reflex sympathetiCdystrophy

Providing the patient is off antibiotics, the sensitivity, specificity, and accuracy of snynovial fluid aspiration is 100%. AntibiotiCadministration before or during the aspiration will mask the analysis

The process of thrombosis starts during the preparation of the femoral canal. Elevation in thrombogeniCfactors is most pronounced during preparation of the femoral canal, especially with insertion of a cemented femoral component. Mechanical manipulation of the limb (dislocation of the femoral head) may also cause intimal damage or occlusion of the femoral vein

Modulus of elasticities are as follows in Gpa (psi 3 106 ): Compact bone: 21 (3)
Titanium: 96 (14) Stainless steel: 193 (28) Cobalt-chrome: 235 (34)

Stress risers are generated when a screw is removed from the femur, weakening the bone for at least 4 weeks. Larger defects (50%) of the cortical width can reduce torsional strength up to 44%. Bypassing the defect by two cortical diameters with a cemented stem doubles the boneâs strength

The most severe stress shielding occurs with an extensively porous-coated chrome-cobalt stem. Stress shielding occurs as the load is transferred from the hip joint to the proximal femur. The load that was previously carried by the hip joint is now shared with the implant. This change leads to remodeling of the proximal femur, resulting in a decreased density and thinning of the proximal portion of the femur. In a group of patients characterized as having severe stress-shielding based on plain radiographs, no adverse effects were noted in terms of hip scores, presence of osteolysis, or need for revision

Noncircumferential-porous coating allows a pathway for particulate debris (polywear) to the distal part of the stem, promoting osteolysis. The polyethylene wear debris migrates through the pathway promoting osteolysis and, ultimately, failure