Indications/Contraindications
Operative management is the treatment of choice for the majority of displaced patellar fractures. Surgical options include open reduction and internal fixation (ORIF), partial or complete patellectomy, with the choice of treatment dependent on the fracture pattern and the amount of comminution. Although there is no widely accepted classification system for patellar fractures, most are based on an anatomic descriptive classification. Important factors include the location of fracture, direction of fracture lines, and the amount of comminution. In the AO/OTA classification, the patella is delineated as 45 and subdivided into A, B, or C depending on whether the fracture is extra-articular, partial articular without disruption of the extensor mechanism, or complete articular with disruption of the extensor mechanism. For the most part, 45B patella fractures are managed nonoperatively whereas 45A and 45C fractures require surgery.
The patella is an integral component of the extensor mechanism of the knee as well as an articular component of the knee joint. The patella’s position in the body and the nature of its role in lower-limb function cause it to be susceptible to injury. Traction forces that pull the patella cephalad are the result of several different vectors caused by contraction of the quadriceps muscle. The quadriceps muscle, extensor retinaculum, along with the iliotibial band, participates in knee extension. The undersurface of the patella, which articulates with the notch of the femur, has the thickest cartilage found in the body. It is this articulation that acts as a fulcrum for extension. Forces measured at the patellofemoral articulation can be over seven times body weight during routine activities such as stair climbing and squatting. Tensile forces can be well over 3,000 N. The importance of the patella for normal knee function cannot be overestimated. Patellectomy results in the loss of the patellar fulcrum, a decrease in the moment arm, and relative lengthening of the quadriceps. This can lead to instability of the knee, extension lag, atrophy of the quadriceps, and loss of extension strength. Therefore, whenever possible, the patella should be repaired rather than excised.
Total patellectomy is generally indicated when the patella is so severely comminuted that an acceptable reduction and stable fixation cannot be achieved with internal fixation.
P.380
Partial patellectomy is indicated for cases that have severe comminution of either the inferior or superior pole that is not amenable to ORIF techniques.
ORIF is indicated for displaced patellar fractures that have fragments large enough to be reduced and stably repaired and is the treatment of choice for the majority of displaced patellar fractures in physiologically young patients. Many comminuted fractures can be salvaged. The goal of surgery is to achieve anatomic reduction of the articular surface with restoration of the continuity of the extensor mechanism. Displacement more than 3 mm and articular incongruity of more than 2 mm are considered strong indications for surgical treatment.
Contraindications and relative contraindications to surgical treatment include nondisplaced or minimally displaced stable fracture patterns. Also, contused or injured skin that precludes safe surgical approaches to the fracture, active infection involving the extremity with the patellar fracture, and medical conditions of the patient that would preclude safe surgical intervention are contraindications for surgery.The Mobile-bearing Tibial Revision Tray
A tibial revision system must allow the surgeon the options of adjunctive stem fixation, methods to manage bone loss, and various levels of prosthetic constraint. The mobile-bearing tibial revision tray (Figure 5) serves as a stable and versatile foundation in the revision knee setting by offering abundant intraoperative options and a platform to compensate for severe bone loss and soft-tissue deficiencies.
The mobile-bearing tibial revision knee tray encompasses a wide array of options to assist the revision knee surgeon when handling bony and soft-tissue deficiencies. There are multiple sizes of tibial components to allow for proximal tibial coverage. Stepped metaphyseal sleeves allow for the filling of bony defects and superior metaphyseal compressive loading. Trial sleeves are sequentially broached until bony defects are overcome and solid fixation in the metaphyseal bone is achieved. Tibial augmentations are also available to manage uncontained bony defects, allowing the surgeon to achieve a stable platform on good bone for excellent fixation. Cemented or uncemented tibial diaphyseal stems are available in various lengths and diameters, offering the knee surgeon flexibility in achieving a stable construct. The mobile-bearing tibial revision tray allows the revision surgeon to accomplish the goals of filling substantial bony defects, restoring the joint line, and providing a strong foundation for solid fixation with compressive loading of bone.
Indications/Contraindications
Operative management is the treatment of choice for the majority of displaced patellar fractures. Surgical options include open reduction and internal fixation (ORIF), partial or complete patellectomy, with the choice of treatment dependent on the fracture pattern and the amount of comminution. Although there is no widely accepted classification system for patellar fractures, most are based on an anatomic descriptive classification. Important factors include the location of fracture, direction of fracture lines, and the amount of comminution. In the AO/OTA classification, the patella is delineated as 45 and subdivided into A, B, or C depending on whether the fracture is extra-articular, partial articular without disruption of the extensor mechanism, or complete articular with disruption of the extensor mechanism. For the most part, 45B patella fractures are managed nonoperatively whereas 45A and 45C fractures require surgery.
The patella is an integral component of the extensor mechanism of the knee as well as an articular component of the knee joint. The patella’s position in the body and the nature of its role in lower-limb function cause it to be susceptible to injury. Traction forces that pull the patella cephalad are the result of several different vectors caused by contraction of the quadriceps muscle. The quadriceps muscle, extensor retinaculum, along with the iliotibial band, participates in knee extension. The undersurface of the patella, which articulates with the notch of the femur, has the thickest cartilage found in the body. It is this articulation that acts as a fulcrum for extension. Forces measured at the patellofemoral articulation can be over seven times body weight during routine activities such as stair climbing and squatting. Tensile forces can be well over 3,000 N. The importance of the patella for normal knee function cannot be overestimated. Patellectomy results in the loss of the patellar fulcrum, a decrease in the moment arm, and relative lengthening of the quadriceps. This can lead to instability of the knee, extension lag, atrophy of the quadriceps, and loss of extension strength. Therefore, whenever possible, the patella should be repaired rather than excised.
Total patellectomy is generally indicated when the patella is so severely comminuted that an acceptable reduction and stable fixation cannot be achieved with internal fixation.
P.380
Partial patellectomy is indicated for cases that have severe comminution of either the inferior or superior pole that is not amenable to ORIF techniques.
ORIF is indicated for displaced patellar fractures that have fragments large enough to be reduced and stably repaired and is the treatment of choice for the majority of displaced patellar fractures in physiologically young patients. Many comminuted fractures can be salvaged. The goal of surgery is to achieve anatomic reduction of the articular surface with restoration of the continuity of the extensor mechanism. Displacement more than 3 mm and articular incongruity of more than 2 mm are considered strong indications for surgical treatment.
Contraindications and relative contraindications to surgical treatment include nondisplaced or minimally displaced stable fracture patterns. Also, contused or injured skin that precludes safe surgical approaches to the fracture, active infection involving the extremity with the patellar fracture, and medical conditions of the patient that would preclude safe surgical intervention are contraindications for surgery.The Mobile-bearing Tibial Revision Tray
A tibial revision system must allow the surgeon the options of adjunctive stem fixation, methods to manage bone loss, and various levels of prosthetic constraint. The mobile-bearing tibial revision tray (Figure 5) serves as a stable and versatile foundation in the revision knee setting by offering abundant intraoperative options and a platform to compensate for severe bone loss and soft-tissue deficiencies.
The mobile-bearing tibial revision knee tray encompasses a wide array of options to assist the revision knee surgeon when handling bony and soft-tissue deficiencies. There are multiple sizes of tibial components to allow for proximal tibial coverage. Stepped metaphyseal sleeves allow for the filling of bony defects and superior metaphyseal compressive loading. Trial sleeves are sequentially broached until bony defects are overcome and solid fixation in the metaphyseal bone is achieved. Tibial augmentations are also available to manage uncontained bony defects, allowing the surgeon to achieve a stable platform on good bone for excellent fixation. Cemented or uncemented tibial diaphyseal stems are available in various lengths and diameters, offering the knee surgeon flexibility in achieving a stable construct. The mobile-bearing tibial revision tray allows the revision surgeon to accomplish the goals of filling substantial bony defects, restoring the joint line, and providing a strong foundation for solid fixation with compressive loading of bone.
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