Incidence and Mechanism of the Pivot Shift

The purpose of this study was to evaluate the effect of the iliotibial band (ITB) on the kinematics of anterior cruciate ligament (ACL) intact and deficient knees and also on the in situ force in the ACL during a simulated pivot shift test. A combination of 10 N-m valgus and 5 N-m internal tibial torques was applied to 10 human cadaveric knees at 158, 308, 458, and 608 of flexion using a robotic/universal force-moment sensor testing system. ITB forces of 0, 22, 44, and 88 N were also applied. An 88 N ITB force significantly decreased coupled anterior tibial translation of ACL deficient knees by 32%-45% at high flexion angles, but did not have a significant effect at low flexion angles. Further, an 88 N ITB force significantly decreased in situ forces in the ACL at all flexion angles by 23%-40%. These results indicate that during the pivot shift test, the ITB can improve tibial reduction at high flexion angles while not affecting subluxation at low flexion angles. Additionally, the action of the ITB as an ACL agonist suggests that its use as an ACL graft might hinder knee stability in response to rotatory load. ß

Section: Discussionmentioning

confidence: 65%

Section: Discussionmentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of the iliotibial band on knee biomechanics during a simulated pivot shift test

Yamamoto

Hsu

Fisk

et al. 2006

The transpatellar approach for the knee in the laboratory

Merican

Ghosh

Deehan

et al. 2009

Self Cite

This paper describes a longitudinal patellar-splitting approach to the knee that includes provision for accurate reconstruction. Our in vitro experiments showed that patellofemoral kinematics and length-change patterns of specific bands of the peripatellar retinacula were not changed significantly by opening and closing the knee via the transpatellar approach. This surgical approach will be useful for in vitro experiments on the knee, when effects due to alterations of internal structures such as cruciate ligament reconstructions or joint replacement are to be studied, avoiding confounding effects caused by changes to the retinacula. In the past, the patellar splitting approach was considered a reasonable option for gaining wide exposure of the knee. Insall credited Sir Robert Jones for the patellar splitting approach.1 In 1971, Insall modified this incision to retain inherent advantages of excellent exposure, but eliminate the disadvantages of splitting the patella.1 His incision elevated the soft tissue overlying the patella, but distally still split the patellar tendon. Splitting the patella was used in case reports for osteochondritis dessicans 2 and exploration and meniscectomy.3 Henderson 4 utilized the incision to obtain good exposure for difficult cases in removal of loose bodies. 5 In pediatric physeal fractures of the distal femur, he recognized the importance of accurate reduction of the articular surface, and therefore did not hesitate to perform a wide exposure by splitting the patella.6 However, around the same time, the medial parapatellar approach was described to gain adequate exposure of the knee without splitting the patella. 7 We are involved in biomechanical work to characterize changes in kinematics and ligament length as a result of surgical intervention and prosthesis geometry. So as not to change the properties of the extensor retinacula, we explored the utility of the patellar splitting approach for laboratory use. Our aim here was to verify that significant changes in kinematics and length changes of the attachments of the extensor retinacula (the lateral retinaculum and the medial and lateral patellofemoral ligament) did not occur with a patellar splitting approach. Our hypothesis was that a longitudinal patellasplitting approach allows adequate access to the knee but does not impact patellofemoral kinematics or the extensor retinacula length. MATERIALS AND METHODS Specimen PreparationNine fresh-frozen cadaveric knees (mean age ¼ 64 years, SD ¼ 16 years) were obtained from the International Institute for the Advancement of Medicine (Jessup, PA). The institute undertook screening and consent for their use for research. Ethical permission for the study was obtained from the Riverside Research Ethics Committee. The knees were stored at À208C and thawed a day prior to experimentation.The skin and subcutaneous tissue were removed. The deep fascia, retinacula, and iliotibial band (ITB) were preserved. The femur and tibia were cut approximately 20 and 15 cm above and below the knee...

Iliotibial band tension reduces patellar lateral stability

Merican

Iranpour

Amis

2009

Self Cite

This study investigated the effect of loading the iliotibial band (ITB) on the stability of the patellofemoral joint. We measured the restraining force required to displace the patella 10 mm medially and laterally (defined as medial and lateral stability, respectively) in 14 fresh-frozen knees from 0 to 908 knee flexion. The testing rig allowed the patella to rotate and translate freely during this displacement. The quadriceps was separated into five components and loaded with 175 N total tension. Testing was performed at 0 to 90 N ITB tension. With no ITB tension, the lateral restraining force ranged from 82 to 101 N across 0 to 908 flexion. Increasing ITB tension caused progressive reduction of the lateral restraining force. The maximum reduction was 25% at 608 flexion and 90 N ITB tension. Medial restraining force increased progressively with increasing knee flexion and increasing ITB loads; it ranged from 74 N at 08 knee flexion and 0 N ITB tension to 211 N at 908 knee flexion and 90 N ITB tension. The maximum effect was an increase of medial restraining force of 50% at 908 flexion and 90 N ITB tension. ß