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    Next Generation Knee Replacements: A New Approach to Replicate the Function of the ACL
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    Abstract:
    Current total knee replacements solve the problem of arthritic knee joints, but the evidence is that normal patterns of knee motions are not restored (1) In addition; paradoxical anterior sliding of the femur on the tibia can occur in the first half of the flexion range (2). Achieving natural motion is likely to be important for daily activities which involve higher angles of flexion, in terms of restoring normal soft tissue lengths and patello-femoral mechanics. Studies have shown the damaging effects of anterior femoral slide on the tibia affecting both the patella and the patellar tendon (3). Our paper examines new knee replacement designs which incorporate geometrical features to regain anatomical knee motion.
    Keywords:
    Knee flexion
    Biomechanics
    Quadriceps tendon
    A common problem after proximal tibia prosthetic reconstruction is insufficient extensor mechanism or extensor lag. Maintaining the reconstructed patellar tendon length is an important way to minimize extensor lag. We measured the patellar tendon length and extensor lag serially. From 1994-2003, seven consecutive patients with malignant bone tumors of the proximal tibia had prosthetic reconstruction. The extensor mechanism was reconstructed by reattachment of the patellar tendon to the prosthesis with a synthetic material and augmented by a gastrocnemius flap. The patellar tendon length was measured according to the Insall-Salvati ratio. The ratios at 30 degrees knee flexion decreased immediately postoperatively, and reverted to almost the same preoperative values within 18 months. The mean ratios at 60 degrees knee flexion are significantly greater than 30 degrees at 6 months postoperatively. These findings indicate that the patellar tendon stretched, whereas the extensor lag improved continuously for 12 months postoperatively. In the revision at 22 months postoperatively, although the patellar tendon was not reattached to the replaced prosthesis, the ratio and the extensor lag had not worsened. These results show that providing strong continuity of the patellar tendon, gastrocnemius flap, and leg extensors can decrease the extensor lag, although the patellar tendon stretches.
    Patellar ligament
    Quadriceps tendon
    This study quantified in-vivo 3D patellar tendon kinematics during weight-bearing deep knee bend beyond 150°. Each knee was MRI scanned to create 3D bony models of the patella, tibia, femur, and the attachment sites of the patellar tendon on the distal patella and the tibial tubercle. Each attachment site was divided into lateral, central, and medial thirds. The subjects were then imaged using a dual fluoroscopic image system while performing a deep knee bend. The knee positions were determined using the bony models and the fluoroscopic images. The patellar tendon kinematics was analyzed using the relative positions of its patellar and tibial attachment sites. The relative elongations of all three portions of the patellar tendon increased similarly up to 60°. Beyond 60°, the relative elongation of the medial portion of the patellar tendon decreased as the knee flexed from 60° to 150° while those of the lateral and central portions showed continuous increases from 120° to 150°. At 150°, the relative elongation of the medial portion was significantly lower than that of the central portion. In four of seven knees, the patellar tendon impinged on the tibial bony surface at 120° and 150° of knee flexion. These data may provide useful insight into the intrinsic patellar tendon biomechanics during a weight-bearing deep knee bend and could provide biomechanical guidelines for future development of total knee arthroplasties that are intended to restore normal knee function.
    Weight-bearing
    Biomechanics
    Patellar ligament
    Knee flexion
    Quadriceps tendon
    Citations (14)
    This study showed the assumption of patellar tendon inextensibility was not valid, and the strain in the patellar tendon was higher than previously reported for other human tendons. The in vivo three-dimensional velocity profiles for the patella, femur, and tibia were measured noninvasively in 18 healthy knees during a low load extensor task using cine phase contrast magnetic resonance imaging. These data were used to calculate patellar tendon elongation and strain. Average maximum strains of 6.6% were found for a low load extension task at relatively small knee angles.
    Strain (injury)
    Patellar ligament
    Quadriceps tendon
    Biomechanics
    Objective To provide anatomy data of the tendon of quadriceps femoris for reconstructing cruciate ligament of knee joint.Methods On 10 adult cadavaric lower limb specimens(20 knee joints),anatomic features of the patellar insertion of quadriceps femoris tendon were investigated.The length and width of the tendon of rmusculus rectus and the thickness of upper patellar pole were measured respectively.Results The patellar insertion width of rectus femoris was about(3.20±0.33)cm,and the original width(1.28±0.25)cm.The length of tendon tissue was(6.96±0.80)cm.The proximal four-fifths of rectus femoris was fully discrete,but the one-fifths of distal end fused with vastus lateralis and vastus intermedius,and formed the quadriceps femoris tendon,which inserted to the three-fourths upper pole anterior aspect of the patella.The average thickness of the upper pole of patella was(2.22±0.14) cm.Conclusions Given of the anatomic features of quadriceps femoris tendon,it is suitable for reconstructing the cruciate ligament of knee joint using this tendon.
    Quadriceps tendon
    Quadriceps femoris muscle
    Patellar ligament
    Rectus femoris muscle
    Citations (0)
    Current total knee replacements solve the problem of arthritic knee joints, but the evidence is that normal patterns of knee motions are not restored (1) In addition; paradoxical anterior sliding of the femur on the tibia can occur in the first half of the flexion range (2). Achieving natural motion is likely to be important for daily activities which involve higher angles of flexion, in terms of restoring normal soft tissue lengths and patello-femoral mechanics. Studies have shown the damaging effects of anterior femoral slide on the tibia affecting both the patella and the patellar tendon (3). Our paper examines new knee replacement designs which incorporate geometrical features to regain anatomical knee motion.
    Knee flexion
    Biomechanics
    Quadriceps tendon
    Citations (1)
    The current report presents the case of a 41-year-old male exhibiting a giant cell tumor of the tendon sheath (GCT-TS) arising from the patellar tendon sheath. Plain radiography and magnetic resonance imaging revealed a well-localized mass that wrapped around the patellar tendon, and extended from the subcutis into the infrapatellar fat pad and tibia. Following histopathological determination of the diagnosis, a piecemeal resection was performed. Nodular-type GCT-TS occurs less frequently in large joints compared with the small joints of the fingers and toes. The current report presents the unique features of a case of GCT-TS extending around the patellar tendon, and invading into the knee joint and proximal tibia bone.
    Tendon sheath
    Quadriceps tendon
    Infrapatellar fat pad
    Patellar ligament
    Citations (8)