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Andrew A. Amis - One of the best experts on this subject based on the ideXlab platform.
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The effect of femoral component rotation on the extensor Retinaculum of the knee
Journal of orthopaedic research : official publication of the Orthopaedic Research Society, 2010Co-Authors: Kanishka M. Ghosh, Azhar M. Merican, Farhad Iranpour, David J. Deehan, Andrew A. AmisAbstract:Malrotation of the femoral component may cause patellofemoral complications after total knee replacement (TKR). We hypothesized that femoral component malrotation would cause excessive lengthening of the retinacula. Retinacular length changes were measured by threading fine sutures along them and attaching these to the patella and to displacement transducers. The knee post-TKR was flexed-extended while the quadriceps were tensed, then the measurements repeated after rotating the femoral component 5° internally and then 5° externally. Internal rotation shortened the medial patellofemoral ligament (MPFL) significantly from 100° to 0° extension. External rotation lengthened the MPFL significantly from 90° to 0° extension. The transverse fibers of the Lateral Retinaculum showed no significant differences. The MPFL attaches directly from bone to bone, so it was lengthened directly by movement of the trochlea and patella, whereas the deep transverse fibers of the Lateral Retinaculum attach to the mobile iliotibial tract, so they were not lengthened directly. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1136–1141, 2010
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THE EFFECT OF TOTAL KNEE REPLACEMENT ON THE EXTENSOR Retinaculum
2009Co-Authors: Kanishka M. Ghosh, Azhar M. Merican, Farhad Iranpour, David J. Deehan, Andrew A. AmisAbstract:Objective: The aim of the study was to test the hypothesis that insertion of a total knee replacement (TKR) may effect range of motion as a consequence of excessive stretching of the retinaculae. Methods: 8 fresh frozen cadaver knees were placed on a customised testing rig. The femur was rigidly fixed allowing the tibia to move freely through an arc of flexion. The quadriceps were loaded to 175N in their physiologic lines of action using a cable, pulley and weight system. The iliotibial tract was loaded with 30N. Tibiofemoral flexion and extension was measured using an optical tracking system. Monofilament sutures were passed along the fibres of the medial patellofemoral ligament (MPFL) and the deep transverse band in the Lateral Retinaculum with the anterior ends attached to the patella. The posterior suture ends were attached to ‘Linear Variable Displacement Transducers’. Thus small changes in ligament length were recorded by the transducers. Ligament length changes were recorded every 10° from 90° to 0° during an extension cycle. A transpatellar approach was used when performing the TKR to preserve the medial and Lateral retinaculae. Testing was conducted on an intact knee and following insertion of a cruciate retaining TKR (Genesis II). Statistical analysis was performed using a two way ANOVA test. Results: The MPFL had a mean behaviour close to isometric, while the Lateral Retinaculum slackened by a mean of 6mm as the knee extended from 60 degrees (Fig 1). After knee replacement there was no statistically significant difference seen in ligament length change patterns in the MPFL, however the Lateral Retinaculum showed significant slackening from 10 to 0°. Conclusion: The data does not support the hypothesis that insertion of a TKR causes abnormal stretching of the retinaculuae. This result relates specifically to the TKR design tested.
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The structural properties of the Lateral Retinaculum and capsular complex of the knee
Journal of biomechanics, 2009Co-Authors: Azhar M. Merican, Farhad Iranpour, Sanjay Sanghavi, Andrew A. AmisAbstract:Although Lateral retinacular releases are not uncommon, there is very little scientific knowledge about the properties of these tissues, on which to base a rationale for the surgery. We hypothesised that we could identify specific tissue bands and measure their structural properties. Eight fresh-frozen knees were dissected, and the Lateral soft tissues prepared into three distinct structures: a broad tissue band linking the iliotibial band (ITB) to the patella, and two capsular ligaments: patellofemoral and patellomeniscal. These were individually tensile tested to failure by gripping the patella in a vice jaw and the soft tissues in a freezing clamp. Results: the ITB–patellar band was strongest, at a mean of 582 N, and stiffest, at 97 N/mm. The patellofemoral ligament failed at 172 N with 16 N/mm stiffness; the patellomeniscal ligament failed at 85 N, with 13 N/mm stiffness. These structural properties suggest that most of the load in-vivo is transmitted to the patella by the transverse fibres that originate from the ITB.
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The effect of overstuffing the patellofemoral joint on the extensor Retinaculum of the knee
Knee surgery sports traumatology arthroscopy : official journal of the ESSKA, 2009Co-Authors: Kanishka M. Ghosh, Azhar M. Merican, Farhad Iranpour, David J. Deehan, Andrew A. AmisAbstract:Overstuffing the patellofemoral compartment during TKR leads to complications such as maltracking and wear, predisposing to early failure. However, there is no data describing how the patellar construct thickness affects the retinacula. This study instrumented cadaveric knees that had a Genesis II (Smith & Nephew, Memphis, TN, USA) TKR in situ. Sutures were passed along the medial patellofemoral ligament (MPFL) and the deep transverse fibre band of the Lateral Retinaculum, from the ilio-tibial band (ITB) to the patella. These sutures were attached to displacement transducers. Length changes in the retinacula were measured during knee flexion-extension against the actions of 175 N quadriceps and 30 N ITB tensions. This was done with the natural patellar thickness, then repeated with the patella 2 mm thinner, 2 mm thicker and 4 mm thicker (overstuffed). Each thickness change caused a significant overall slackening or stretching of the MPFL (P < 0.0001 by ANOVA), with 2.3 mm mean stretching (P < 0.001 all angles of knee flexion by post-testing) at 4 mm thicker. The ITB-patellar band was not slackened (P = 0.491) or stretched (P = 0.346) significantly by 2 mm thickness changes. 4 mm thickening stretched the Lateral Retinaculum 1.1 mm (P = 0.0108). Patellar thickness affected the MPFL more than the Lateral Retinaculum. This difference reflected the mobile attachment of the Lateral Retinaculum to the ITB, whereas the MPFL was stretched directly between bony attachments. 2 mm overstuffing did not stretch the retinacula sufficiently to cause mechanical effects.
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Anatomy of the Lateral Retinaculum of the knee.
The Journal of bone and joint surgery. British volume, 2008Co-Authors: Azhar M. Merican, Andrew A. AmisAbstract:Anatomical descriptions of the Lateral Retinaculum have been published, but the attachments, name or even existence of its tissue bands and layers are ill-defined. We have examined 35 specimens of the knee. The deep fascia is the most superficial layer and the joint capsule is the deepest. The intermediate layer is the most substantial and consists of derivatives of the iliotibial band and the quadriceps aponeurosis. The longitudinal fibres of the iliotibial band merge with those of the quadriceps aponeurosis adjacent to the patella. These longitudinal fibres are reinforced by superficial arciform fibres and on the deep aspect by transverse fibres of the iliotibial band. The latter are dense and provide attachment of the iliotibial band to the patella and the tendon of vastus Lateralis obliquus. Our study identifies two important new findings which are a constant connection of the deep fascia to the quadriceps tendon superior and Lateral to the patella, and, a connection of the deeper transverse fibres to the tendon of vastus Lateralis obliquus.
Vicente Sanchis-alfonso - One of the best experts on this subject based on the ideXlab platform.
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Deep Transverse Lateral Retinaculum Reconstruction for Medial Patellar Instability
Arthroscopy techniques, 2015Co-Authors: Vicente Sanchis-alfonso, Erik Montesinos-berry, Joan Carles Monllau, Jack T. AndrishAbstract:Medial patellar instability can be a disabling complication of an extensive Lateral Retinaculum release. It is often overlooked, and for the diagnosis, it is necessary to have a high index of suspicion. Typically, the patient feels a new pain and new instability after the Lateral Retinaculum release that are distinct from, and much worse than, those before surgery. All of our patients had significant relief from their pain with "reverse" McConnell taping. If there is a significant improvement in symptoms after this taping and stress radiographs or stress axial computed tomography scans show an objective pathologic medial patellar displacement, reconstruction of the Lateral Retinaculum should be considered. This article details our technique for reconstruction of the deep transverse layer of the Lateral Retinaculum using an anterior strip of the iliotibial band. This strip is detached from its insertion onto the Gerdy tubercle and then reflected proximally beyond the level of the Lateral femoral epicondyle. Finally, it is attached either by direct suture to the remaining prepatellar and peripatellar Retinaculum if there is adequate tissue present or by a suture anchor.
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Iatrogenic Medial Patellar Instability: An Avoidable Injury.
Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the Internation, 2015Co-Authors: Vicente Sanchis-alfonso, Alan C. MerchantAbstract:Iatrogenic medial patellar instability is a specific condition that frequently causes incapacitating anterior knee pain, severe disability, and serious psychological problems. The diagnosis should be suspected in a patient who has undergone previous patellar realignment surgery that has made the pain worse. The diagnosis can be established by physical examination and simple therapeutic tests (e.g., "reverse" McConnell taping) and confirmed by imaging techniques. This iatrogenic condition should no longer exist and could almost be eliminated by avoiding over-release of the Lateral Retinaculum.
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Results of Isolated Lateral Retinacular Reconstruction for Iatrogenic Medial Patellar Instability
Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the Internation, 2014Co-Authors: Vicente Sanchis-alfonso, Erik Montesinos-berry, Joan Carles Monllau, Alan C. MerchantAbstract:Purpose The aim of this study was to assess the outcomes of an isolated Lateral Retinaculum reconstruction for iatrogenic medial patellar instability (IMPI) in patients with continued pain after failed Lateral retinacular release (LRR), including associated psychometric analysis. Methods Pain was assessed using the visual analog scale (VAS) and disability was determined with the Lysholm scale. Psychological variables such as anxiety, depression, catastrophizing, and fear-of-movement beliefs were studied by using self-administered psychometric questionnaires. Results All 17 patients (13 women and 4 men) in this retrospective study had undergone LRR previously for anterior knee pain or Lateral patellar instability. Four patients had undergone LRR plus proximal (Insall) realignment, and one had undergone LRR plus a medial tibial tubercle transfer. After their procedures, all had disabling symptoms. All patients underwent reconstructive surgery for IMPI. At a minimum follow-up of 2 years (range, 2 to 8 years), the mean preoperative VAS score was 7.6 (range, 5 to 9) and improved to 1.9 (range, 0 to 8) at the time of final follow-up ( P P Conclusions Reconstruction of the deep transverse layer of the Lateral Retinaculum (LR) using a central strip of the iliotibial band for IMPI in patients with continued pain after failed LRR can successfully treat these severely disabled patients. Level of Evidence Level IV, therapeutic case series.
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Biological Causes of Anterior Knee Pain
Anterior Knee Pain and Patellar Instability, 2011Co-Authors: Vicente Sanchis-alfonso, Esther Roselló-sastre, Juan Saus-mas, Fernando Revert-rosAbstract:We review the pathophysiology of anterior knee pain in the young patient. Emphasis is placed on newer findings. We have developed what we call the “Neural Model” as an explanation for the genesis of anterior knee pain. We have demonstrated a neuroanatomical basis for PFPS in the young patient and the clinical observation that the Lateral Retinaculum may have a key role in the origin of this pain. According to our studies we hypothesize that periodic short episodes of ischemia in the Lateral Retinaculum could be implicated in the pathogenesis of anterior knee pain, at least in a subgroup of anterior knee pain patients, by triggering neural proliferation of nociceptive axons (substance P positive nerves), mainly in a perivascular location. Our findings are compatible with the tissue homeostasis theory widely accepted currently to explain the genesis of anterior knee pain. If the “neural model” of anterior knee pain proves to have a certain validity, it would lead in many cases to therapeutic recommendations to alleviate pain more effectively and safer than the attempts to correct “malalignment.” Moreover, we believe that instability in patients with PFPS can be explained, at least in part, because of the damage of nerves of the Lateral Retinaculum which can be related with proprioception. Our findings, however, do not preclude the possibility of pain arising in other anatomical structures such as infrapatellar fat pad, synovium and subchondral bone.
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Gait pattern normalization after Lateral Retinaculum reconstruction for iatrogenic medial patellar instability.
The Knee, 2007Co-Authors: Vicente Sanchis-alfonso, Roger Torga-spak, Alex CortesAbstract:A case of medial patellar instability following Insall's proximal realignment studied pre- and postoperatively by gait analysis is presented. Preoperative gait analysis showed an increased stance time period as well as an increased horizontal braking, heel contact and toe-off vertical peak forces on the affected limb. In our case, gait parameters tended to shift towards a normal value pattern after reconstruction of the Lateral Retinaculum. We speculate about the importance of the passive restraining structures in patellar stability, in contrast to the role of the muscle function advocated by some authors.
Azhar M. Merican - One of the best experts on this subject based on the ideXlab platform.
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The effect of femoral component rotation on the extensor Retinaculum of the knee
Journal of orthopaedic research : official publication of the Orthopaedic Research Society, 2010Co-Authors: Kanishka M. Ghosh, Azhar M. Merican, Farhad Iranpour, David J. Deehan, Andrew A. AmisAbstract:Malrotation of the femoral component may cause patellofemoral complications after total knee replacement (TKR). We hypothesized that femoral component malrotation would cause excessive lengthening of the retinacula. Retinacular length changes were measured by threading fine sutures along them and attaching these to the patella and to displacement transducers. The knee post-TKR was flexed-extended while the quadriceps were tensed, then the measurements repeated after rotating the femoral component 5° internally and then 5° externally. Internal rotation shortened the medial patellofemoral ligament (MPFL) significantly from 100° to 0° extension. External rotation lengthened the MPFL significantly from 90° to 0° extension. The transverse fibers of the Lateral Retinaculum showed no significant differences. The MPFL attaches directly from bone to bone, so it was lengthened directly by movement of the trochlea and patella, whereas the deep transverse fibers of the Lateral Retinaculum attach to the mobile iliotibial tract, so they were not lengthened directly. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1136–1141, 2010
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THE EFFECT OF TOTAL KNEE REPLACEMENT ON THE EXTENSOR Retinaculum
2009Co-Authors: Kanishka M. Ghosh, Azhar M. Merican, Farhad Iranpour, David J. Deehan, Andrew A. AmisAbstract:Objective: The aim of the study was to test the hypothesis that insertion of a total knee replacement (TKR) may effect range of motion as a consequence of excessive stretching of the retinaculae. Methods: 8 fresh frozen cadaver knees were placed on a customised testing rig. The femur was rigidly fixed allowing the tibia to move freely through an arc of flexion. The quadriceps were loaded to 175N in their physiologic lines of action using a cable, pulley and weight system. The iliotibial tract was loaded with 30N. Tibiofemoral flexion and extension was measured using an optical tracking system. Monofilament sutures were passed along the fibres of the medial patellofemoral ligament (MPFL) and the deep transverse band in the Lateral Retinaculum with the anterior ends attached to the patella. The posterior suture ends were attached to ‘Linear Variable Displacement Transducers’. Thus small changes in ligament length were recorded by the transducers. Ligament length changes were recorded every 10° from 90° to 0° during an extension cycle. A transpatellar approach was used when performing the TKR to preserve the medial and Lateral retinaculae. Testing was conducted on an intact knee and following insertion of a cruciate retaining TKR (Genesis II). Statistical analysis was performed using a two way ANOVA test. Results: The MPFL had a mean behaviour close to isometric, while the Lateral Retinaculum slackened by a mean of 6mm as the knee extended from 60 degrees (Fig 1). After knee replacement there was no statistically significant difference seen in ligament length change patterns in the MPFL, however the Lateral Retinaculum showed significant slackening from 10 to 0°. Conclusion: The data does not support the hypothesis that insertion of a TKR causes abnormal stretching of the retinaculuae. This result relates specifically to the TKR design tested.
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THE EFFECT OF PATELLOFEMORAL OVERSTUFF ON THE EXTENSOR Retinaculum FOLLOWING TOTAL KNEE REPLACEMENT
2009Co-Authors: Km Ghosh, Azhar M. Merican, Farhad Iranpour, David J. Deehan, A. A. AmisAbstract:Objective: This study tested the hypothesis that complications resulting from overstuffing the patellofemoral joint after total knee replacement (TKR) may be a consequence of excessive stretching of the retinaculae. Methods: 8 fresh frozen cadaver knees were placed on a customised testing rig. The femur was rigidly fixed and the tibia moved freely through an arc of flexion. The quadriceps and iliotibial tract were physiologically loaded to 205N using a cable, pulley and weight system. Tibiofemoral flexion/extension was measured using an optical tracking system. Monofilament sutures were passed along the fibres of the medial patellofemoral ligament (MPFL) and the deep transverse band in the Lateral Retinaculum with the anterior ends attached to the patella. The posterior suture ends were attached to ‘Linear Variable Displacement Transducers’. Thus, small changes in ligament length were recorded by the transducers. Length changes were recorded every 10° from 90°- 0° during an extension cycle. A transpatellar approach was used when performing the TKR to preserve the medial and Lateral retinaculae. Testing was conducted following insertion of a cruciate retaining TKR (Genesis II). The patella was resurfaced and various patellar thicknesses were achieved by placing 2mm thick nylon washers behind the ‘onlay’ button. The thicknesses measured were 2mm understuff, pre-cut thickness, 2 and 4mm overstuff. Statistical analysis was performed using a two way ANOVA test. Results: Patellar understuff resulted in the MPFL slackening an average of 1.6mm from 60 to 0° (p Conclusion: Overstuffing the PFJ stretches the MPFL, because it attaches directly between two bones. The Lateral Retinaculum attaches to the relatively mobile ITT, so overstuffing does not stretch it.
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The structural properties of the Lateral Retinaculum and capsular complex of the knee
Journal of biomechanics, 2009Co-Authors: Azhar M. Merican, Farhad Iranpour, Sanjay Sanghavi, Andrew A. AmisAbstract:Although Lateral retinacular releases are not uncommon, there is very little scientific knowledge about the properties of these tissues, on which to base a rationale for the surgery. We hypothesised that we could identify specific tissue bands and measure their structural properties. Eight fresh-frozen knees were dissected, and the Lateral soft tissues prepared into three distinct structures: a broad tissue band linking the iliotibial band (ITB) to the patella, and two capsular ligaments: patellofemoral and patellomeniscal. These were individually tensile tested to failure by gripping the patella in a vice jaw and the soft tissues in a freezing clamp. Results: the ITB–patellar band was strongest, at a mean of 582 N, and stiffest, at 97 N/mm. The patellofemoral ligament failed at 172 N with 16 N/mm stiffness; the patellomeniscal ligament failed at 85 N, with 13 N/mm stiffness. These structural properties suggest that most of the load in-vivo is transmitted to the patella by the transverse fibres that originate from the ITB.
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The effect of overstuffing the patellofemoral joint on the extensor Retinaculum of the knee
Knee surgery sports traumatology arthroscopy : official journal of the ESSKA, 2009Co-Authors: Kanishka M. Ghosh, Azhar M. Merican, Farhad Iranpour, David J. Deehan, Andrew A. AmisAbstract:Overstuffing the patellofemoral compartment during TKR leads to complications such as maltracking and wear, predisposing to early failure. However, there is no data describing how the patellar construct thickness affects the retinacula. This study instrumented cadaveric knees that had a Genesis II (Smith & Nephew, Memphis, TN, USA) TKR in situ. Sutures were passed along the medial patellofemoral ligament (MPFL) and the deep transverse fibre band of the Lateral Retinaculum, from the ilio-tibial band (ITB) to the patella. These sutures were attached to displacement transducers. Length changes in the retinacula were measured during knee flexion-extension against the actions of 175 N quadriceps and 30 N ITB tensions. This was done with the natural patellar thickness, then repeated with the patella 2 mm thinner, 2 mm thicker and 4 mm thicker (overstuffed). Each thickness change caused a significant overall slackening or stretching of the MPFL (P < 0.0001 by ANOVA), with 2.3 mm mean stretching (P < 0.001 all angles of knee flexion by post-testing) at 4 mm thicker. The ITB-patellar band was not slackened (P = 0.491) or stretched (P = 0.346) significantly by 2 mm thickness changes. 4 mm thickening stretched the Lateral Retinaculum 1.1 mm (P = 0.0108). Patellar thickness affected the MPFL more than the Lateral Retinaculum. This difference reflected the mobile attachment of the Lateral Retinaculum to the ITB, whereas the MPFL was stretched directly between bony attachments. 2 mm overstuffing did not stretch the retinacula sufficiently to cause mechanical effects.
Kent N. Bachus - One of the best experts on this subject based on the ideXlab platform.
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Soft Tissue Restraints to Lateral Patellar Translation in the Human Knee
American Journal of Sports Medicine, 2016Co-Authors: Stephen M. Desio, Robert T. Burks, Kent N. BachusAbstract:The purpose of this investigation was to identify and quantify the soft tissue restraints, both medially and Laterally, to Lateral patellar translation. These restraints to Lateral patellar translation at 20 degrees of knee flexion were tested biomechanically on a universal testing instrument in nine fresh-frozen cadaveric knees. After preconditioning the tissues, the patella of each intact knee was translated Laterally to a distance at which a force of 200 N was recorded. This distance was used to translate the patella for the remaining structures to be sectioned. The contribution of each structure to the total restraining force was determined as the percent of the force to restrain the intact specimen by sectioning the restraints in a predetermined order. The contribution of each structure to the restraining force was defined as the difference between the restraining force before and after its sectioning. The medial patellofemoral ligament was found to be the primary restraint to Lateral patellar translation at 20 degrees of flexion, contributing 60% of the total restraining force. The medial patellomeniscal ligament contributed 13% of the total force, and the Lateral Retinaculum contributed 10%. The medial patellotibial ligament and superficial fibers of the medial Retinaculum were not functionally important in preventing Lateral translation. The previously unrecognized contribution of the Lateral Retinaculum as a restraint to Lateral patellar translation may shed new light on the failures of isolated Lateral release for acute Lateral dislocation of the patella.
Stephen J. Incavo - One of the best experts on this subject based on the ideXlab platform.
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Does TKR Lead to an Increase in Lateral Retinacular Strain With Flexion
Journal of Bone and Joint Surgery-british Volume, 2013Co-Authors: Philip C. Noble, R. Patel, Kashif Ashfaq, Derek T. Bernstein, Sabir K. Ismaily, Stephen J. IncavoAbstract:Introduction After TKR, excessive tension within the Lateral Retinaculum can lead to joint instability, component wear, stiffness and pain. The spatial distribution of strain in the Lateral retinculum is unknown, both in the native knee and after TKR. In this study we measure the magnitude and distribution of mechanical strain in the Lateral Retinaculum with knee flexion, both in the native knee and after TKR. We hypothesize that: 1.Strain in the Lateral Retinaculum will increase as a function of flexion. 2.Some regions of the Lateral Retinaculum experience greater strain than others. 3.TKR will affect the magnitude and location of strain during knee flexion. Materials and Methods A fiduciary grid of approximately 40–70 markers was attached to the exposed Lateral retinacula of five fresh frozen cadaveric knees in order to allow tracking of soft-tissue deformation. Each knee was flexed from 0–120° in a 6 degree-of-freedom custom activity simulator that physiologically loaded the knee during a squatting maneuver. During simulation, the displacement of each fiduciary point was measured using visible-light stereo-photogrammetry. The fiduciary grid divided into four distinct regions for strain analysis. Using the grid of the native knee in full extension as the initial state, the average principal strain in each region was calculated as a function of flexion. Measurements were repeated after TKR was performed using a contemporary implant system. Results In the native knee, average retinacular strain increased dramatically with knee flexion (30°: 12% vs 120°: 25%; p = 0.007). The greatest strain was observed in the supero-Lateral region in high flexion (34% at 120°). No significant change in strain with flexion was seen in the infero-medial region bordering the patellar ligament (10% at 30° to 15% at 120°; p > 0.05). After TKR, retinacular strains increased by an average of 13% in extension when compared to the native knee. In flexion, strains decreased following arthroplasty by an average of 4% at 30° and 6% at all other angles. The largest strains were observed in the supero-Lateral region and were comparable to strain observed in the native knee (34% at 120°). The greatest decrease in strain after TKR was observed in the supero-medial region (26% vs 16% at 90°). Conclusions In the native knee, average Lateral retinacular strains are greatest mid- to high-flexion as the Retinaculum tightens to constrain patellar motion. The superior regions of the Retinaculum, where the iliotibial band-patellar fibers are located, experience the most strain, especially in higher flexion. After TKR, strain in the supero-medial region decreases while strain in the supero-Lateral region remains comparable to the native knee, suggesting the geometry of the native knee along
