Trochlear Contact Pressures after Straight Anteriorization of the Tibial Tuberosity

2008 ◽  
Vol 36 (10) ◽  
pp. 1953-1959 ◽  
Author(s):  
John-Paul H. Rue ◽  
Anne Colton ◽  
Stephanie M. Zare ◽  
Elizabeth Shewman ◽  
Jack Farr ◽  
...  
Keyword(s):  
Contact Area ◽  
Clinical Relevance ◽  
Knee Flexion ◽  
Patellofemoral Joint ◽  
Pressure Sensors ◽  
Contact Forces ◽  
Tibial Tuberosity ◽  
Before And After ◽  
The Mean ◽  
Contact Pressures

Background Anteromedialization of the tibial tuberosity has been shown to decrease mean total contact pressures of the lateral trochlea and to shift contact pressures to the medial trochlea. Hypothesis Modifying the anteromedialization osteotomy to a straight anteriorization osteotomy of the tibial tuberosity can decrease trochlear contact pressures without a resultant medial shift of forces to the medial trochlear contact area. Study Design Controlled laboratory study. Methods Ten cadavers were tested before and after straight anteriorization tibial tuberosity osteotomy by loading the extensor mechanism with 89.1 and 178.2 N at 0°, 30°, 60°, and 90° of flexion following a validated patellofemoral joint loading protocol. Contact pressures were measured with electroresistive pressure sensors placed directly on the trochlea. Results The mean trochlear contact pressures after osteotomy decreased significantly ( P < .05) for loads of 89.1 and 178.2 N at both 30° (23% and 20%, respectively) and 60° (18.7% and 31.9%, respectively) of knee flexion. The peak contact pressures decreased significantly ( P < .05) for loads of 89.1 and 178.2 N at 30° (24.3% and 27.0%, respectively) and 60° (31.9% and 24.5%, respectively) and for loads of 89.1 N at 90° (13.4%) of knee flexion. Conclusion The authors demonstrated significantly decreased trochlear contact forces after straight anteriorization osteotomy of the tibial tuberosity, without a significant resultant medial shift of the center of force. Clinical Relevance Straight anteriorization of the tibial tuberosity may be a useful adjunct for patients with medial articular defects of the patellar or trochlea in whom anteromedialization would be otherwise contraindicated.

Trochlear Contact Pressures after Anteromedialization of the Tibial Tubercle

2005 ◽  
Vol 33 (11) ◽  
pp. 1710-1715 ◽  
Author(s):  
Paul R. Beck ◽  
Andre L. Thomas ◽  
Jack Farr ◽  
Paul B. Lewis ◽  
Brian J. Cole
Keyword(s):  
Contact Pressure ◽  
Knee Flexion ◽  
Patellofemoral Joint ◽  
Tibial Tubercle ◽  
Chondral Defects ◽  
Cartilage Restoration ◽  
Before And After ◽  
The Mean ◽  
Femoral Side ◽  
Contact Pressures

Background Anteromedialization is recommended for cartilage restoration of patellofemoral defects, with the presumption that it decreases contact pressures across the trochlea. No study has evaluated pressures on the trochlear side of the patellofemoral joint after anteromedialization of the tibial tubercle. Hypothesis Anteromedialization of the tibial tubercle decreases contact pressure across the trochlea. Study Design Controlled laboratory study. Methods Ten cadaveric knees were tested by placing an electroresistive pressure sensor on the femoral side of the patellofemoral joint. A validated model of nonweightbearing resisted extension was simulated by loading the extensor mechanism at 89.1 N and 178.2 N. Knees were tested 3 times per load at 30°, 60°, 90°, and 105°. The center of force and pressure across the patellofemoral articulation were compared before and after a reproducible and consistent anteromedialization. Results The mean center of force shifted medially after anteromedialization at 89.1 N and 178.2 N. At 89.1 N, the mean total contact pressure decreased significantly (P <. 05) at all angles, and at 178.2 N, it decreased significantly at 30°, 60°, and 90° of knee flexion. The mean lateral trochlear contact pressure decreased significantly (P <. 05) at all flexion angles at both 89.1 N and 178.2 N. The mean central trochlear contact pressure decreased significantly (P <. 05) at 30° with the 89.1-N and 178.2-N loads but increased significantly (P <. 05) at 90° with the 89.1-N load. The mean medial trochlear contact pressure increased significantly (P <. 05) at all flexion angles at 89.1 N and 178.2 N. Conclusion Anteromedialization shifts the contact force to the medial trochlea and decreases the mean total contact pressure. Clinical Relevance Anteromedialization decreases the mean total contact pressure while shifting contact pressure toward the medial trochlea. This study suggests that anteromedialization is appropriate for unloading the lateral trochlea. However, this procedure appears to have minimal benefit on central chondral defects, and it may actually increase the load in patients with medial defects.

Effect of Patellar Tendon Shortening on Tracking of the Patella

2005 ◽  
Vol 33 (10) ◽  
pp. 1565-1574 ◽  
Author(s):  
Neil Upadhyay ◽  
Samuel R. Vollans ◽  
Bahaa B. Seedhom ◽  
Roger W. Soames
Keyword(s):  
Patellar Tendon ◽  
Contact Area ◽  
Knee Flexion ◽  
Patellofemoral Joint ◽  
Contact Stresses ◽  
Contact Areas ◽  
Before And After ◽  
Joint Contact ◽  
Joint Biomechanics ◽  
Patellar Tendon Shortening

Background Although 10% postoperative patellar tendon shortening after bone–patellar tendon–bone autograft reconstruction of the anterior cruciate ligament has been reported, there are no published studies assessing the effect of shortening on patellofemoral joint biomechanics under physiological loading conditions. Purpose To investigate the influence of patellar tendon shortening on patellofemoral joint biomechanics. Study Design Controlled laboratory study. Methods The authors evaluated the patellofemoral contact area, the location of contact, and the patellofemoral joint reaction force and contact stresses in 7 cadaveric knees before and after 10% patellar tendon shortening. Shortening was achieved using a specially designed device. Experimental conditions simulating those occurring during level walking were employed: physiological quadriceps loads and corresponding angles of tibial rotation were applied at 15 °, 30 °, and 60 ° flexion of the knee. Patellofemoral joint contact areas were measured before and after shortening using the silicone oil–carbon black powder suspension squeeze technique. Results After patellar tendon shortening, patellofemoral joint contact areas were displaced proximally on the patellar surface and distally on the femoral surface. Although the contact area increased by 18% at 15 ° of knee flexion (P=. 04), no significant change occurred at 30 ° or 60 ° of knee flexion (P>. 05). Patellofemoral contact stress remained unchanged after patellar tendon shortening (P>. 05) at each flexion angle. Conclusion Our results suggest that a 10% shortening of the patellar tendon does not alter patellar contact stresses during locomotion. It is not clear whether apparent changes in contact location in all positions and contact area at 15 ° would have clinical consequences.

A Novel Quantitative Approach for Evaluating Contact Mechanics of Meniscal Replacements

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
E. Linder-Ganz ◽  
J. J. Elsner ◽  
A. Danino ◽  
F. Guilak ◽  
A. Shterling
Keyword(s):  
Contact Area ◽  
Peak Pressure ◽  
Contact Forces ◽  
Articular Surfaces ◽  
Joint Contact ◽  
Bench Testing ◽  
Contact Pressures ◽  
Implant Dislocation ◽  
Total Contact Area

One of the functions of the meniscus is to distribute contact forces over the articular surfaces by increasing the joint contact areas. It is widely accepted that total/partial loss of the meniscus increases the risk of joint degeneration. A short-term method for evaluating whether degenerative arthritis can be prevented or not would be to determine if the peak pressure and contact area coverage of the tibial plateau (TP) in the knee are restored at the time of implantation. Although several published studies already utilized TP contact pressure measurements as an indicator for biomechanical performance of allograft menisci, there is a paucity of a quantitative method for evaluation of these parameters in situ with a single effective parameter. In the present study, we developed such a method and used it to assess the load distribution ability of various meniscal implant configurations in human cadaveric knees (n=3). Contact pressures under the intact meniscus were measured under compression (1200 N, 0 deg flexion). Next, total meniscectomy was performed and the protocol was repeated with meniscal implants. Resultant pressure maps were evaluated for the peak pressure value, total contact area, and its distribution pattern, all with respect to the natural meniscus output. Two other measures—implant-dislocation and implant-impingement on the ligaments—were also considered. If any of these occurred, the score was zeroed. The total implant score was based on an adjusted calculation of the aforementioned measures, where the natural meniscus score was always 100. Laboratory experiments demonstrated a good correlation between qualitative and quantitative evaluations of the same pressure map outputs, especially in cases where there were contradicting indications between different parameters. Overall, the proposed approach provides a novel, validated method for quantitative assessment of the biomechanical performance of meniscal implants, which can be used in various applications ranging from bench testing of design (geometry and material of an implant) to correct implant sizing.

Contact Forces Acting on Large Femoral Osteochondral Allografts During Forced Knee Extension

2017 ◽  
Vol 45 (12) ◽  
pp. 2804-2811 ◽  
Author(s):  
Peter Z. Du ◽  
Keith L. Markolf ◽  
Christopher J. Lama ◽  
David R. McAllister ◽  
Kristofer J. Jones
Keyword(s):  
Clinical Relevance ◽  
Knee Extension ◽  
Load Cell ◽  
Contact Forces ◽  
Osteochondral Allograft ◽  
Human Knee ◽  
Native Bone ◽  
Load Cells ◽  
The Mean ◽  
Femoral Condyles

Background: A single cylindrical graft plug is commonly used for large focal femoral defects during osteochondral allograft (OCA) transplantation. Excessive contact force (CF) on a proud plug could compromise initial healing. CFs during forced knee extension are of particular interest because this maneuver is used by therapists to restore early postoperative range of motion. Hypothesis: A proud OCA plug will significantly increase the CF and significantly decrease the knee extension angle (KEA). Study Design: Controlled laboratory study. Methods: Eleven human knee specimens had miniature load cells installed in both femoral condyles at standardized locations representative of clinical defects. Each load cell had a 20-mm–diameter cylinder of native bone/cartilage attached at its precise anatomic location. Four spacers, 0.5 mm in thickness, were inserted sequentially between each load cell and its mounting bracket to create proud plug conditions of 0.5 to 2 mm. Measurements of the CF and KEA were recorded at extension moment levels up to 8 N·m. Results: At 8 N·m, the mean CFs for flush plugs were 149 ± 18 N (lateral) and 34 ± 13 N (medial). The mean increases in the medial CF (compared with flush) for 0.5-mm, 1-mm, 1.5-mm, and 2-mm proud conditions were 31 N (+91%), 64 N (+188%), 111 N (+325%), and 154 N (+451%), respectively. Corresponding increases for lateral proud plugs were 55 N (+37%), 120 N (+81%), 162 N (+109%), and 210 N (+141%), respectively. The CFs (and CF increases) for lateral grafts were significantly ( P < .05) higher than corresponding values for medial grafts at each proudness condition. Medial plug proudness had no consistent effect on the KEA. A 1-mm proud lateral plug significantly reduced the KEA by −1.6° (0 N·m) and −0.9° (2 N·m). Conclusion: Graft proudness of only 0.5 mm significantly increased CFs during forced knee extension, emphasizing the surgical precision necessary to achieve normal CF levels. Clinical Relevance: It is believed that some amount of CF is beneficial in the early stages of graft healing, and our findings suggest that forced knee extension may be well suited for this purpose. However, the surgeon should be aware that large extension moments can also generate relatively high CFs, especially if the plug is proud.

Abdomen-Thigh Contact During Forward Reaching Tasks in Obese Individuals

2013 ◽  
Vol 29 (5) ◽  
pp. 517-524 ◽  
Author(s):  
Bhupinder Singh ◽  
Thomas D. Brown ◽  
John J. Callaghan ◽  
H. John Yack
Keyword(s):  
Healthy Subjects ◽  
Force Plate ◽  
Contact Forces ◽  
Daily Activities ◽  
Pressure Mapping ◽  
Reaching Tasks ◽  
The Mean ◽  
The Moment ◽  
Contact Pressures ◽  
Force Plate Data

During seated forward reaching tasks in obese individuals, excessive abdominal tissue can come into contact with the anterior thigh. This soft tissue apposition acts as a mechanical restriction, altering functional biomechanics at the hip, and causing difficulty in certain daily activities such as bending down, or picking up objects from the floor. The purpose of the study was to investigate the contact forces and associated moments exerted by the abdomen on the thigh during seated forward-reaching tasks in adult obese individuals. Ten healthy subjects (age 58.1 ± 4.4) with elevated BMI (39.04 ± 5.02) participated in the study. Contact pressures between the abdomen and thigh were measured using a Tekscan Conformat pressure-mapping sensor during forward-reaching tasks. Kinematic and force plate data were obtained using an infrared motion capture system. The mean abdomen-thigh contact force was 10.17 ± 5.18% of body weight, ranging from 57.8 N to 200 N. Net extensor moment at the hip decreased by mean 16.5 ± 6.44% after accounting for the moment generated by abdomen-thigh tissue contact. In obese individuals, abdomen-thigh contact decreases the net moment at the hip joint during seated forward-reaching activities. This phenomenon should be taken into consideration for accurate biomechanical modeling in these individuals.

scholarly journals Patellofemoral joint contact area increases with knee flexion and weight-bearing

2005 ◽  
Vol 23 (2) ◽  
pp. 345-350 ◽  
Author(s):  
Thor F. Besier ◽  
Christine E. Draper ◽  
Garry E. Gold ◽  
Gary S. Beaupré ◽  
Scott L. Delp
Keyword(s):  
Contact Area ◽  
Knee Flexion ◽  
Patellofemoral Joint ◽  
Weight Bearing ◽  
Joint Contact

EFFECTS OF SIMULATED FIXED FEMORAL ROTATION ON THE PATELLOFEMORAL JOINT: IN VITRO AND IN VIVO BIOMECHANICAL ASSESSMENT IN CANINES

2000 ◽  
Vol 04 (02) ◽  
pp. 97-105 ◽  
Author(s):  
Thay Q Lee ◽  
Michele M. Schulz ◽  
Patrick J. McMahon
Keyword(s):  
Knee Flexion ◽  
Patellofemoral Joint ◽  
In Vitro Study ◽  
Femoral Rotation ◽  
Rotational Deformity ◽  
Biomechanical Assessment ◽  
Biomechanical Evaluation ◽  
Contact Pressures

The quantitative effects of fixed femoral rotation on the patellofemoral joint were assessed in canines in vitro and in vivo. For the in vitro study, ten canine knees were examined in neutral and 30 degrees of internal and external fixed femoral rotations. Fuji film was inserted into the patellofemoral joint and quadriceps loading was simulated at 60 and 90 degrees of knee flexion. There was significant increase in patellofemoral contact pressures on the contralateral facets of the patella with 30 degrees of fixed femoral rotation at both knee flexion angles (p < 0.05). For the in vivo study, 12 skeletally mature mongrel dogs were subjected to either internal or external bilateral femoral rotational deformity of 30 degrees. Three animals served as controls. Biomechanical evaluation of the articular cartilage showed a statistically significant decrease for both the unrelaxed and relaxed apparent shear modulus at six months for both internal and external femoral rotations (p < 0.05) in comparison to the control. In vivo results from fixed femoral rotation on the patellofemoral joint correlate with that expected from in vitro biomechanical results. The results from this study suggest that rotational deformity of the femur should be corrected within six months to prevent patellofemoral joint arthrosis.

The Effect of Lateral Opening Wedge Distal Femoral Varus Osteotomy on Tibiofemoral Contact Mechanics Through Knee Flexion

2018 ◽  
Vol 46 (13) ◽  
pp. 3237-3244 ◽  
Author(s):  
James D. Wylie ◽  
Bastian Scheiderer ◽  
Elifho Obopilwe ◽  
Joshua B. Baldino ◽  
Colin Pavano ◽  
...  
Keyword(s):  
Contact Pressure ◽  
Contact Area ◽  
Knee Flexion ◽  
Plate Fixation ◽  
Lateral Compartment ◽  
Opening Wedge ◽  
Full Extension ◽  
Varus Osteotomy ◽  
Before And After ◽  
Lateral Opening Wedge

Background: Lateral opening wedge distal femoral osteotomy (DFO) unloads a diseased lateral compartment of the knee in patients with genu valgum. To the best of our knowledge, there are no biomechanical studies investigating the effect of knee flexion on contact pressure and area after DFO. Hypothesis: As knee flexion angles increase, DFO will be less effective at unloading the lateral compartment of the knee. Study Design: Controlled laboratory study. Methods: Lateral opening wedge DFO was performed, correcting a mean of 7°, in 10 cadaveric knees using plate fixation. Tibiofemoral contact pressure was measured in 0°, 15°, 30°, 45°, 60°, and 75° of knee flexion before and after osteotomy using electronic sensors. Peak contact pressure (PCP), mean contact pressure (MCP), and contact area were measured for each condition. Anatomic dissection quantified the tibiofemoral contact position on the distal femur in all degrees of flexion. Mixed-effects regression analyses were used to compare the change in variables before and after osteotomy and between flexion angles. Results: One sample had to be excluded because of tibiofemoral arthritis. MCP decreased in the lateral compartment after DFO throughout all degrees of flexion (all P < .05) but to the greatest extent in 0° of flexion. When examining the percentage of MCP in the lateral compartment, this decreased after DFO at 0° (70.4% to 40.0%; P < .001), 15° (65.1% to 52.1%; P < .001), 30° (60.7% to 52.0%; P = .003), 45° (55.8% to 49.7%; P = .033), and 60° (51.9% to 44.2%; P = .010) but not at 75° (50.2% to 45.3%; P = .112). PCP decreased in the lateral compartment after DFO at 0° (2.41 to 1.34 MPa; P < .001), 15° (2.50 to 1.81 MPa; P < .001), 30° (2.28 to 1.93 MPa; P = .039), 45° (2.21 to 1.73 MPa; P = .005), 60° (2.15 to 1.71 MPa; P = .009), and 75° (1.95 to 1.49 MPa; P = .012). The percentage of contact area decreased in the lateral compartment in full extension (68.7% to 48.1%; P = .007) but not at any other degree of flexion (all P > .05). Conclusion: DFO decreased lateral compartment pressure. However, it had the greatest effect in full knee extension. Clinical Relevance: DFO decreased contact pressure in the lateral compartment but more effectively decreased contact pressure in the more anterior aspects of the femoral articular cartilage.

scholarly journals Evaluation of body posture in nursing students

2017 ◽  
Vol 51 (0) ◽  
Author(s):  
Marília Fernandes Andrade ◽  
Érika de Cássia Lopes Chaves ◽  
Michele Rita Oliveira Miguel ◽  
Talita Prado Simão ◽  
Denismar Alves Nogueira ◽  
...  
Keyword(s):  
Nursing Students ◽  
Knee Flexion ◽  
Total Sample ◽  
Mean Value ◽  
The Body ◽  
Body Posture ◽  
Before And After ◽  
Practice Method ◽  
The Mean ◽  
Two Stages

Abstract OBJECTIVE To investigate the body posture of nursing students before and after clinical practice. METHOD The study was developed in two stages. Initially the body posture of students of the 2nd, 4th, 6th, and 8th periods were assessed through photogrammetry. All images were analyzed in a random and masked manner with CorporisPro® 3.1.3 software. Three evaluations were performed for each angle and then the mean value was calculated. Two years later, when the 4th period students had developed their clinical internships, their body posture was again evaluated. RESULTS The total sample consisted of 112 students. Comparison of their posture with the normality pattern showed that all the angles presented significant differences (p< 0.00), except for the angle of the Thales triangle. Reassessment of these students evidenced significant differences in the angles of the acromioclavicular joint (p=0.03), knee flexion (p< 0.00) and in the tibiotarsal angle (p< 0.00). CONCLUSION All the students presented alterations when compared to the normality values. The segments that presented significant differences between before and after practice were the acromioclavicular angle, knee flexion, and tibiotarsal angle; the latter two were in the rolling position.

Influence of Screw Type on Obtained Contact Area and Contact Force in a Cadaveric Subtalar Arthrodesis Model

2002 ◽  
Vol 23 (11) ◽  
pp. 986-991 ◽  
Author(s):  
Beat Hintermann ◽  
Victor Valderrabano ◽  
Benno Nigg
Keyword(s):  
Contact Force ◽  
Contact Area ◽  
Contact Forces ◽  
Maximum Pressure ◽  
Compression Force ◽  
Articular Surfaces ◽  
Fresh Frozen ◽  
Compression Mechanism ◽  
The Mean

The purpose of this study was to compare the compression effect of the 7.0-AO screw and the 6.5 mm Ideal Compression Screw (I.CO.S.) screw in an in vitro subtalar arthodesis model. Six fresh-frozen, human cadaver foot specimens were obtained for analysis. The subtalar joint was opened laterally without affecting the articular surfaces. A Tekscan 5051 sensor with a maximum pressure of 250 PSI and a sensel-density of 62 sensel/sq-cm was placed into the joint, which allowed for continuous measurement of the contact area and contact forces achieved by one 7.0 AO-screw, and thereafter by one 6.5 I.CO.S.-screw. When tightening the screw, mean contact area increased by 0.21 cm 2 for the AO-screw (p<0.05), and by 0.27 cm 2 for the I.CO.S.-screw (p>0.05). When comparing the tightened AO-screw and I.CO.S.-screw, mean contact area increased from 1.40 cm 2 to 1.97 cm 2 (p<0.05). The mean contact force also increased when tightening the screws. This increase was 7.6 N for the AO-screw (p<0.05) and 14.8 N for the I.CO.S.-screw (p>0.05). When comparing the tightened AO-screw and I.CO.S.-screw, mean contact force increased from 54.9 N to 81.7 N (p<0.05). The obtained results have shown that the design of the screw influences the achieved compression force. The superior compression of the I.CO.S.-screw might be explained by the better gripping and additional compression mechanism of its head. The shape of the head of the cannulated AO-screw, in contrast, may be critical to resist against the weak cortical bone of the calcaneus, i.e. it can sink into soft bone resulting in a loss of compression force.

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