scholarly journals Effect of Patella Alta on the Native Anatomometricity of the Medial Patellofemoral Complex: A Cadaveric Study

2020 ◽  
Vol 8 (7_suppl6) ◽  
pp. 2325967120S0045
Author(s):  
Hailey Huddleston ◽  
Kevin Campbell ◽  
Michael Redondo ◽  
Alejandro Espinoza ◽  
Jorge Chahla ◽  
...  
Keyword(s):  
Quadriceps Tendon ◽  
Length Change ◽  
Patella Alta ◽  
Constant Length ◽  
Cadaveric Specimen ◽  
Inferior Aspect ◽  
Attachment Sites ◽  
Custom Made ◽  
Length Changes ◽  
Medial Patellofemoral Complex

Objectives: Patella alta has been identified as an important risk factor for lateral patellar instability and medial patellofemoral complex (MPFC) reconstruction failure. To our knowledge, no prior study has analyzed the anisometry of the MPFC in the setting of patella alta as this may play a role in the postoperative outcomes and could affect surgical technique. Methods: Eight (n=8) fresh frozen cadaveric knees were used in this study. No IRB approval was needed at our institution due to the use of cadaveric specimen. The MPFC was identified and dissected along with the patellar tendon, and quadriceps tendon. A custom-made jig was utilized to evaluate MPFC lengths from 0-90° of flexion. Length was measured at four possible reconstruction locations (midpoint patella [MP], MPFC osseous center [FC], superior medial pole of the patella [SM], and quadriceps tendon [Q]) along the extensor mechanism using a 3D robotic arm. These measurements were repeated at 0, 20, 40, 60 and 90° degrees of flexion. Degrees of increasing severity of patella alta at Caton-Deschamps index (CDI) ratios of 1.0, 1.2, 1.4, and 1.6, were then investigated. Results: CDI and attachment sites significantly affect changes in MPFC length from 0-90° of flexion (p < 0.0005). Proximal attachment points had more robust length changes than distal ones and increases in CDI enhanced these differences. Point Q at CDI 1 was similar to SM at 1.2 (p = 0.234), SM and FC at 1.4 (p = 0.89 and p = 0.073) and FC at 1.6 (p = 0.928). SM at CDI of 1 was similar to FC at 1.2 and 1.4 (p = 0.414 and p = 0.503) and MP at 1.6 (p = 0.473), while FC at CDI 1 was similar to the FC at 1.2 (p = 0.157) and MP at 1.4 and 1.6 (p = 0.068 and p = 0.519). Finally, the MP was similar at CDI 1.2 (p = 0.888) and 1.4 (p = 0.385) compared to at CDI of 1. At the quadriceps points, MPFC length and flexion degrees showed a moderate negative linear correlation at a CDI of 1 (r = -0.484, p = 0.002) and 1.6 (r = -0.692, p < 0.0005) (Fig 1). At the MP location at a CDI ratio of 1.6, significant differences were seen at 0° vs 90° (p = 0.027), 0° vs 60° (p = 0.044), 0° vs 40° (p = 0.016), and 0° vs 20° (p = 0.044), suggesting differing length change properties between the Q and MP attachment sites. Conclusions: Anisometry varies with location of the patellar attachment and with patellar height within the MPFC. The superior aspect of the MPFC demonstrated the most isometric behavior, increasing linearly with increasing flexion. The inferior aspect of the MPFC retains a relatively constant length at 20 to 90° of flexion. Increasing CDI amplified these results. These findings demonstrate that proximal based grafts loosen significantly before engaging in the trochlea and this effect is exaggerated in the setting of patella alta. Furthermore, this data suggests that soft tissue surgical reconstructions may be modified to correct for patella alta in place of performing distalization, which carries significant morbidity.

Effect of Patella Alta on the Native Anatomometricity of the Medial Patellofemoral Complex: A Cadaveric Study

2020 ◽  
Vol 48 (6) ◽  
pp. 1398-1405
Author(s):  
Adam B. Yanke ◽  
Hailey P. Huddleston ◽  
Kevin Campbell ◽  
Michael L. Redondo ◽  
Alejandro Espinoza ◽  
...  
Keyword(s):  
Attachment Site ◽  
Quadriceps Tendon ◽  
Length Change ◽  
Patellar Height ◽  
Extensor Mechanism ◽  
Patella Alta ◽  
Similar Length ◽  
Custom Made ◽  
Length Changes ◽  
Medial Patellofemoral Complex

Background: Patella alta has been identified as an important risk factor for lateral patellar instability and medial patellofemoral complex (MPFC) reconstruction failure. Purpose: To evaluate the length changes of the MPFC at multiple possible reconstruction locations along the extensor mechanism in varying degrees of patella alta throughout knee motion. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric knees were used in this study. The MPFC was identified and dissected with the patellar tendon and quadriceps tendon. A custom-made jig was utilized to evaluate lengths from 0° to 90° of flexion with physiological quadriceps loading. Length was measured with a 3-dimensional robotic arm at 4 possible reconstruction locations along the extensor mechanism: the midpoint patella (MP), the MPFC osseous center (FC), the superior medial pole of the patella (SM) at the level of the quadriceps insertion, and 1 cm proximal to the SM point along the quadriceps tendon (QT). These measurements were repeated at 0°, 20°, 40°, 60° and 90° of flexion. Degrees of increasing severity of patella alta at Caton-Deschamps index (CDI) ratios of 1.0, 1.2, 1.4, and 1.6 were then investigated. Results: Patella alta and MPFC attachment site location significantly affected changes in MPFC length from 0° to 90° of flexion ( P< .0005). Length changes at attachment MP showed no difference when CDI 1.0 was compared with all patella alta values (CDI 1.2, 1.4, 1.6; P > .05). Similarly, FC showed no difference in length change from 0° to 90° until CDI 1.6, in contrast to proximal attachments (SM, QT), which demonstrated significant changes at CDI 1.4 and 1.6. When length changes were analyzed at each degree of flexion (0°, 20°, 40°, 60°, 90°), Spearman correlation analysis showed a moderate negative linear correlation for QT at CDI 1.0 ( r= −0.484; P = .002) and 1.6 ( r = −0.692; P < .0005), demonstrating constant loosening at the QT point at normal and elevated patellar height. In contrast, no differences in length were observed for MP at CDI 1.0 throughout flexion, and at CDI 1.6, there was a difference only at 0° ( P < .05). Points FC and MP at CDI 1.6 had similar length change properties to points SM and QT at CDI 1.0 ( P > .05), suggesting that distal attachments in the setting of patella alta may provide similar length changes to proximal attachmentswith normal height. Conclusion: Anisometry of the MPFC varies not only with attachment location on the extensor mechanism but also with patellar height. Increased patellar height leads to more significant changes in anisometry in the proximal MPFC attachment point as compared with the distal component. In the setting of patella alta, including a CD ratio of 1.6, the osseous attachments of the MPFC remain nearly isometric wheras the proximal half length changes increase significantly. Clinical Significance: The results of this study support the idea that the MPFC should be considered as 2 separate entities (proximal medial quadriceps tendon femoral ligament and distal medial patellofemoral ligament) owing to their unique length change properties.

scholarly journals Medial collateral ligament reconstruction graft isometry is effected by femoral position more than tibial position

2021 ◽  
Author(s):  
Christoph Kittl ◽  
James Robinson ◽  
Michael J. Raschke ◽  
Arne Olbrich ◽  
Andre Frank ◽  
...  
Keyword(s):  
Medial Collateral Ligament ◽  
Knee Flexion ◽  
Length Change ◽  
Collateral Ligament ◽  
Complex Behaviour ◽  
Femoral Attachment ◽  
Attachment Sites ◽  
Custom Made ◽  
Length Changes ◽  
Graft Length

Abstract Purpose The purpose of this study was to examine the length change patterns of the native medial structures of the knee and determine the effect on graft length change patterns for different tibial and femoral attachment points for previously described medial reconstructions. Methods Eight cadaveric knee specimens were prepared by removing the skin and subcutaneous fat. The sartorius fascia was divided to allow clear identification of the medial ligamentous structures. Knees were then mounted in a custom-made rig and the quadriceps muscle and the iliotibial tract were loaded, using cables and hanging weights. Threads were mounted between tibial and femoral pins positioned in the anterior, middle, and posterior parts of the attachment sites of the native superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL). Pins were also placed at the attachment sites relating to two commonly used medial reconstructions (Bosworth/Lind and LaPrade). Length changes between the tibiofemoral pin combinations were measured using a rotary encoder as the knee was flexed through an arc of 0–120°. Results With knee flexion, the anterior fibres of the sMCL tightened (increased in length 7.4% ± 2.9%) whilst the posterior fibres slackened (decreased in length 8.3% ± 3.1%). All fibre regions of the POL displayed a uniform lengthening of approximately 25% between 0 and 120° knee flexion. The most isometric tibiofemoral combination was between pins placed representing the middle fibres of the sMCL (Length change = 5.4% ± 2.1% with knee flexion). The simulated sMCL reconstruction that produced the least length change was the Lind/Bosworth reconstruction with the tibial attachment at the insertion of the semitendinosus and the femoral attachment in the posterior part of the native sMCL attachment side (5.4 ± 2.2%). This appeared more isometric than using the attachment positions described for the LaPrade reconstruction (10.0 ± 4.8%). Conclusion The complex behaviour of the native MCL could not be imitated by a single point-to-point combination and surgeons should be aware that small changes in the femoral MCL graft attachment position will significantly effect graft length change patterns. Reconstructing the sMCL with a semitendinosus autograft, left attached distally to its tibial insertion, would appear to have a minimal effect on length change compared to detaching it and using the native tibial attachment site. A POL graft must always be tensioned near extension to avoid capturing the knee or graft failure.

scholarly journals Length change pattern of the medial structures of the knee and related reconstructions

2020 ◽  
Vol 8 (9_suppl7) ◽  
pp. 2325967120S0053
Author(s):  
Arne Olbrich ◽  
Elmar Herbst ◽  
Christoph Domnick ◽  
Johannes Glasbrenner ◽  
Michael J. Raschke ◽  
...  
Keyword(s):  
Medial Collateral Ligament ◽  
Knee Flexion ◽  
Insertion Site ◽  
Length Change ◽  
Collateral Ligament ◽  
Femoral Insertion ◽  
Superficial Medial Collateral Ligament ◽  
Custom Made ◽  
Length Changes ◽  
Length Reduction

Introduction: Aim of the study was to investigate the length changes of the medial structures and related reconstructions. It was assumed that the three fibre sections (anterior/middle/posterior) of the superficial medial collateral ligament (sMCL) have different length change patterns, which cannot be imitated by current reconstructions. Hypotheses: The three fibre sections (anterior/middle/posterior) of the superficial medial collateral ligament (sMCL) cannot be imitated by current reconstructions. Methods: Measurements were made on eight cadaveric knees. The knee joints were clamped in a custom-made open chain extension structure. For this purpose, the portions of the quadriceps and the iliotibial tract were aligned according to their fibre direction and statically loaded using hanging weights. The respective tibial and femoral insertion points of the sMCL anterior/middle/posterior fibres were marked by small pins. Similarly, pins were inserted at the tibial and femoral attachment sites of the posterior oblique ligament (POL). In order to imitate the Lind reconstruction, a pin was additionally inserted on the tibial semitendinosus insertion site. Pin combinations accounting for the anterior/middle/posterior sMCL, the POL, and the Lind reconstruction were connected using a high resistant suture. Then the length change patterns were measured using a rotary encoder from 0-120° knee flexion. Statistical analysis was performed using 2-way repeated-measures ANOVA and a post-hoc Bonferroni correction (p <0.05). Results: The anterior and posterior fibres of the sMCL showed a reciprocal behaviour (p< 0.001). The anterior fibres showed a length reduction (2%) up to a flexion of 20°, followed by an elongation of 5% at 120° flexion, which means that the anterior fibres are tight in knee flexion. Conversely, the posterior fibres of the MCL showed an initial length reduction of 4% at 20° flexion. This was followed by an isometric range (20° - 80°) and a further length reduction of 8% in deep flexion (120°). Thus, the posterior fibres of the MCL were tight in extension. The three parts of the POL showed a constant reduction of 25% between 0° and 120°. The Lind reconstruction with the tibial pin at the semitendinosus insertion site showed similar length changes compared to the sMCL (n.s.). Furthermore, the Lind reconstruction was dependent on the femoral placement of the pins (p <.001). The tibial placement had no significant influence. Conclusion: The anterior portion of the sMCL was tight in flexion, whereas the posterior portion was tight in extension. This reciprocal behavior could not be imitated by a single point to point reconstruction. When surgically applying these reconstructions, special attention should be paid to the femoral insertion.

scholarly journals Simulation of varying femoral attachment sites of medial patellofemoral ligament using a musculoskeletal multi-body model

2015 ◽  
Vol 1 (1) ◽  
pp. 547-551 ◽  
Author(s):  
A. Geier ◽  
T. Tischer ◽  
R. Bader
Keyword(s):  
Knee Flexion ◽  
Medial Patellofemoral Ligament ◽  
Numerical Study ◽  
Patellofemoral Instability ◽  
Length Change ◽  
Systematic Evaluation ◽  
Parameter Study ◽  
Femoral Attachment ◽  
Attachment Sites ◽  
Length Changes

AbstractThe medial patellofemoral ligament (MPFL) is a key structure in the treatment of habitual and traumatic patellofemoral instability. However, there exists little knowledge about its behaviour during deep knee flexion after femoral refixation. Since improper femoral attachment sites may lead to unnatural length change patterns in the ligament and consequently to osteoarthritis due to pathological femoro-patellar contact pressure, the understanding of the patella kinematics and MPFL behaviour is crucial.The purpose of this numerical study was to compute the six-degree-of-freedom motion pattern of the human patella during deep knee flexion for systematic analysis of varying landmarks for the femoral attachment in medial patellofemoral ligament reconstruction surgery by means of multibody simulation.Therefore, based on a previously presented musculoskeletal model [1] the dynamic pathways of the patella were computed. Then, the spatial motion was approximated by rheonomic polynomials and exploited for systematic evaluation of the MPFL length change patterns. Hence, 16 femoral attachment points at a radius of 5 mm and 10 mm around the radiographic centre point [2] were defined and the absolute length changes were recorded during deep knee flexion to 120 degree.This approach allows for a systematic evaluation of numerous MPFL attachment sites while exploiting the physiological patella kinematics. The patella kinematics including shift, flexion, tilt and rotation as well as the MPFL length change patterns were consistent to in vitro and in vivo data in the literature [3–7] and therefore indicate validity of the numerical approach. The parameter study on the femoral attachment site should enable to determine the most isometric point and non-isometric variations corresponding to patellofemoral instability, arthritis or high graft load.

Isometry of potential suture attachment sites for the cranial cruciate ligament deficient canine stifle

2008 ◽  
Vol 21 (03) ◽  
pp. 215-220 ◽  
Author(s):  
J. Kue ◽  
J. Gemma ◽  
S. Roe
Keyword(s):  
Femoral Condyle ◽  
Cruciate Ligament ◽  
Length Change ◽  
Full Extension ◽  
Cranial Cruciate Ligament ◽  
Percent Change ◽  
Caudal Portion ◽  
Attachment Sites ◽  
Length Changes ◽  
A Site

SummaryFor a suture that spans a joint to provide support without limiting range of motion, its attachment points on either side of the joint must remain the same distance from each other from full extension to full flexion. The effect of location of the tibial crest attachment for a fabello- tibial crest suture was studied in seven canine cadaveric stifles. The distance from a fabella marker to each of 11 tibial markers was determined from radiographs of each limb, as it progressed from 150° to 130°, 105°, 90°, 65° and 45° of flexion. The marker locations that were more proximal and cranial on the tibial crest had the least percent change in distance. The effect of anchoring the suture to the femur at a site other than the fabella was investigated using the same radiographs. Five marks were placed in a grid on the caudal portion of the femoral condyle and supracondylar region. The mean percent change in length from each femoral point to the five more proximal and cranial tibial markers was determined. The least change in length occurred for those femoral points located close to the origin of the cranial cruciate ligament. Locations more proximal or cranial resulted in large changes in length, particularly when matched with less ideal tibial locations. Although this study does not directly examine length changes in sutures, it demonstrates that there are some locations for the origin and insertion of an extracapsular suture that are associated with less length change than others, and also forms the basis for future investigations.

The location and mechanism of electromotility in guinea pig outer hair cells

1993 ◽  
Vol 70 (2) ◽  
pp. 549-558 ◽  
Author(s):  
R. Hallworth ◽  
B. N. Evans ◽  
P. Dallos
Keyword(s):  
Guinea Pig ◽  
Hair Cells ◽  
Outer Hair Cell ◽  
Length Change ◽  
Opposite Polarity ◽  
Outer Hair Cells ◽  
Response Amplitude ◽  
Change Function ◽  
Length Changes ◽  
Diameter Change

1. The microchamber method was used to examine the motile responses of isolated guinea pig outer hair cells to electrical stimulation. In the microchamber method, an isolated cell is drawn partway into a suction pipette and stimulated transcellularly. The relative position of the cell in the microchamber is referred to as the exclusion fraction. 2. The length changes of the included and excluded segments were compared for constant sinusoidal stimulus amplitude as functions of the exclusion fraction. Both included and excluded segments showed maximal responses when the cell was excluded approximately halfway. Both segments showed smaller or absent responses when the cell was almost fully excluded or almost fully included. 3. When the cell was near to, but not at, the maximum exclusion, the included segment response amplitude was zero, whereas the excluded segment response amplitude was nonzero. In contrast, when the cell was nearly fully included, the excluded segment response amplitude was zero, but the included segment response amplitude was still detectable. A simple model of outer hair cell motility based on these results suggests that the cell has finite-resistance terminations and that the motors are restricted to a region above the nucleus and below its ciliated apex (cuticular plate). 4. The function describing length change as a function of command voltage was measured for each segment as the exclusion fraction was varied. The functions were similar at midrange exclusions (i.e., when the segments were about equal length), showing nonlinearity and saturability. The functions were strikingly different when the segment lengths were different. The effects of exclusion on the voltage to length-change functions suggested that the nonlinearity and saturability are local properties of the motility mechanism. 5. The diameter changes of both segments were examined. The segment diameter changes were always antiphasic to the length changes. This finding implies that the motility mechanism has an active antiphasic diameter component. The diameter change amplitude was a monotonically increasing function of exclusion for the included segment, and a decreasing function for the excluded segment. 6. The voltage to length-change and voltage to diameter-change functions were measured for the same cell and exclusion fraction. The voltage to diameter-change function was smaller in amplitude than the voltage to length-change function. The functions were of opposite polarity to each other, but were otherwise similar in character. Thus it is likely that the same motor mechanism is responsible for both axial and diameter deformations.

The Monitoring of Shrinkage of the PVA Cement-Plates

2013 ◽  
Vol 438-439 ◽  
pp. 280-282 ◽  
Author(s):  
Michaela Kostelecká ◽  
Jiří Kolísko
Keyword(s):  
Length Change ◽  
Free Shrinkage ◽  
Significant Difference ◽  
Length Changes ◽  
The Difference ◽  
Matrix Influence

This paper presents results of a series of shrinkage tests. Described tests were performed on asbestos-free plates. The shrinkage represents very important role in monitoring of length changes for different orientation of the fibers. The results showed that humidity significantly influenced dimensions change of tested fibrecement plates. Length change ratio of dried plates and saturated plates represented the most significant difference that reached 0.25 %. Influence of fibres orientation on the length change was not confirmed. The difference in both measured direction was the same because of varied humidity impact. Elimination of free shrinkage is predominantly given by matrix, influence of fibers is not significant.

Design and Analysis of Hemispherical Electrostatic Micro Deformable Focusing Mirror

Volume 3 ◽  
2004 ◽  
Author(s):  
Shang-Wei Tsai ◽  
Meng-Ju Lin
Keyword(s):  
Applied Voltage ◽  
Electrostatic Force ◽  
Focal Length ◽  
Length Change ◽  
Least Square ◽  
Limit Values ◽  
Etching Depth ◽  
Isotropic Etching ◽  
Length Changes ◽  
Structure Layer

For uniform deformation, based on bulk microfabrication with isotropic etching, two types of hemispherical electrostatic micro deformable focusing mirror are designed. One of the focusing mirrors is center-anchored, and the other is circular clamped. Using theory of shells, theoretical solution of deformation under uniform electrostatic force is derived. For more detail analysis of the electrostatic and elastic forces coupling problem, finite element is used to analyze the deformation of the mirror structure. Applying electrostatic force, the profile of micro focusing mirror will be not the spherical and change to become a curve like parabolic surface. Using least square method, the curve is fitted as a parabolic curve and the focal lengths of the focusing micro mirror are obtained. The result shows the focal length without applying electrostatic force can be determined by different micro mirror radius and isotropic etching depth. When the electrostatic forces are applied, the deformation and the focal length change differently between the two types of focusing mirror. For circular clamped micro mirror, the deformation is larger near circular clamped region and uniform in the center regime. Therefore, the relation of focal length and applying voltage is a concave curve with minimum values. That is, the focusing length decreasing as the applying voltage increasing and reaches a limit values. When the applying voltage continues increasing after reaching the minimum value, the focal length increases fast. It also shows the thicker structure layer needs larger applied voltage. But the focal length changes in larger stroke. The pull-in voltage is about 100 volt when the structure layer are both 2 μm. However, the pull-in voltage increases nonlinearly as gap increasing. When the gap increases to 4 μm, the pull-in voltage is about 300 volt. The result shows center-anchored micro mirror has better performance. The deformation is more uniform and the focal length increases nonlinearly as applied voltage increasing. It is found the stroke of focal length is larger and the applied voltage is less. The results shows even when the gap and structure layer is 4 and 2 μm, the pull-in voltage is about 62 volts. However, the stoke changes from 990 to about 1320 μm when applying voltage is from 0 to 60 volts. Therefore, with low applied voltage and large focal length stoke, the center-anchored micro mirror has good performance.

Fusimotor axons in the kitten

1986 ◽  
Vol 56 (5) ◽  
pp. 1462-1473 ◽  
Author(s):  
J. E. Gregory ◽  
U. Proske
Keyword(s):  
Structural Parameters ◽  
Muscle Spindles ◽  
Length Change ◽  
Repetitive Stimulation ◽  
Axon Diameter ◽  
Spinal Root ◽  
Excitatory Effect ◽  
Internodal Length ◽  
Constant Length ◽  
Rate Of Increase

In kittens 1- to 23-days old growth of axons in the soleus nerve has been studied using the structural parameters nerve length, internodal length, and axonal diameter. In addition, single functional fusimotor axons were isolated in lumbosacral ventral roots, and the responses of muscle spindles in soleus were studied during fusimotor stimulation. While nerve length over the soleus nerve to lumbar spinal root increased from 41 to 76 mm during the 22 days, mean internodal length increased from 250 to 410 microns. Mean axon diameter increased from 2.1 to 4.1 microns. In the youngest animals values for both internodal length and axon diameter were distributed uniformly about the mean. From day 11 onward the distributions became bimodal, including a growing number of new axons in the small-myelinated range. Filaments of ventral root were isolated that on repetitive stimulation had a specific excitatory effect on the discharge of muscle spindles. The responses could be attributed to axons that were not associated with measurable tension and were therefore likely to be fusimotor fibers. Measurements of the conduction velocity of skeletomotor and fusimotor axons showed that conduction speed increased progressively with age for both groups, but the rate of increase was more than three times faster in the most rapidly conducting skeletomotor axons compared with the fusimotor axons. The distribution of conduction velocities for fusimotor fibers showed two peaks, one in the range typical for conduction in unmyelinated fibers, 0.5-1.0 m/s, the second at 3-4 m/s. The small number of values in the range of 1-2 m/s was attributed to the process of myelination. It is suggested that conduction speed increases discontinuously over this part of the range as impulse conduction changes from continuous propagation to saltatory transmission. Eighteen fusimotor axons could be classified as having either a static or a dynamic action on spindle discharge. Repetitive stimulation of fusimotor fibers during a ramp-and-hold stretch of the muscle produced a characteristic response. Fibers classified as dynamic had little effect on the response of the spindle when the muscle was held at a particular length but greatly increased the response during a length change. Static fusimotor fibers, on stimulation, increased the response of the spindle at constant length but did not evoke a selective increase during the length change. Both kinds of fusimotor effects were characterized by overall low firing rates.

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