The Role of Subtalar Motion and Ankle Contact Pressure Changes from Angular Deformities of the Tibia

Foot & Ankle ◽  
1987 ◽  
Vol 7 (5) ◽  
pp. 290-299 ◽  
Author(s):  
Arthur J. Ting ◽  
Richard R. Tarr ◽  
Augusto Sarmiento ◽  
Ken Wagner ◽  
Charles Resnick
Keyword(s):  
Contact Pressure ◽  
Ankle Joint ◽  
Contact Area ◽  
Subtalar Joint ◽  
Angular Deformity ◽  
Talar Dome ◽  
Posterior Portion ◽  
Fracture Angle ◽  
Tibiotalar Joint ◽  
Angular Deformities

It is a well known entity that fractures of the tibia heal with some component of angular deformity. Ankle and subtalar joints may compensate for small degrees of angular deformities, but the exact amount of malunion that can be accepted without development of late sequalae has yet to be determined. Two recent studies from this institution have concluded that (1) contact changes at the tibiotalar joint tend to be greater with distal third tibial fracture deformities compared to proximal and middle with the ankle in neutral, 5° dorsiflexion, and 20° of plantar flexion. (2) Anterior and posterior bow deformities produced a greater change in contact area of the tibiotalar joint than with valgus or varus deformities. This phenomena may be possibly explained by the subtalar motion in the horizontal plane which averages 23°. Thus, it was the primary purpose of this paper to determine the exact role, if any, in subtalar motion on tibiotalar contact in angular deformities of the tibia. To achieve this objective the subtalar joint was transfixed thereby eliminating its perceived compensatory movement. Six cadaveric lower extremities were disarticulated at the knee joint and stripped of soft tissue preserving capsular and ligamentous structures. A custom universal joint was used to create various angulatory deformities at proximal, middle, and distal third levels of the tibia. Contact pressure across the tibiotalar joint was recorded using pressure-sensitive film and analyzed quantitatively in terms of contact area as well as pattern. The same combinations of angular deformities were then run with the subtalar joint transfixed in neutral. The results indicated that as in the two previous studies distal third deformities resulted in the greatest amount of change in ankle contact pressure area. The data also demonstrated that when subtalar motion was restricted ankle contact area decreased significantly in all planes of angulatory deformity. (1) The data collected agree with the results of two previous studies which showed that there was a decreased in total ankle contact area consistently at the distal third level with posterior angulatory deformities of the tibia. (2) By defining the resultant fracture angle and the foot axis angle a geometric explanation can be given to demonstrate a distal level fracture of the tibia has a greater effect on the ankle articulation than one more proximal. (3) The ankle joint has been shown by others to be less congruent as it moves away from its neutral position. This was found to affect and therefore cause a decrease in ankle contact area with tibial angulatory deformities. (4) The ankle joint is more adapted for weightbearing in neutral and in dorsiflexion. The anterior portion of the talar dome is probably more adapted to weightbearing than the posterior portion. This accounted for greater changes in ankle contact area during plantarflexion than in dorsiflexion. (5) The subtalar joint was found to play a very significant role in maintaining the talus in its normal relationship to the tibia. Restriction of the subtalar joint affected all deformities of the tibia as the resultant fracture angle increased. (6) The data supports Inman's concept of the subtalar joint acting as a torque transmitter and compensates for tibial varus and valgus deformities. (7) Subtalar joint restriction affected varus deformities more than valgus deformities probably due to shifting of the talar dome therefore significantly altering its normal biomechanics.

scholarly journals Effect of Distal Tibial Varus and Valgus Deformity on Tibiotalar Joint Contact

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0025
Author(s):  
Zhao Hong-Mou
Keyword(s):  
Contact Pressure ◽  
Ankle Joint ◽  
Contact Area ◽  
Peak Pressure ◽  
Tibiotalar Joint ◽  
Force Center ◽  
Fibular Osteotomy ◽  
Group I ◽  
Joint Contact ◽  
Group A

Category: Ankle; Basic Sciences/Biologics Introduction/Purpose: To study the effect of different degrees of distal tibial varus and valgus deformities on the tibiotalar joint contact, and to understand the role of fibular osteotomy. Methods: Eight cadaveric lower legs were used for biomechanical study. Nine conditions were included: normal ankle joint (group A), 10° varus (group B), 5° varus (group C), 5° valgus (group D), 10° valgus (group E) with fibular preserved, and 10° varus (group F), 5° varus (group G), 5° valgus (group H), and 10° valgus (group I) after fibular osteotomy. The joint contact area, contact pressure, and peak pressure were tested; and the translation of contact force center was observed. Results: The joint contact area, contact pressure, and peak pressure had no significant difference between group A and groups B to E (P>0.05). After fibular osteotomy, the contact area decreased significantly in groups F and I when compared with group A (P<0.05); the contact pressure increased significantly in groups F, H, and I when compared with group A (P<0.05); the peak pressure increased significantly in groups F and I when compared with group A (P<0.05). There were two main anterior-lateral and anterior-medial contact centers in normal tibiotalar joint, respectively; and the force center was in anterior-lateral part, just near the center of tibiotalar joint. While the fibula was preserved, the force center transferred laterally with increased varus angles; and the force center transferred medially with increased valgus angles. However, the force center transferred oppositely to the medial part with increased varus angles, and laterally with increased valgus angles after fibular osteotomy. Conclusion: Fibular osteotomy facilitates the tibiotalar contact pressure translation, and is helpful for ankle joint realignment in suitable cases.

scholarly journals The Role of Calcaneofibular Ligament (CFL) Injury in Ankle Instability

2017 ◽  
Vol 2 (3) ◽  
pp. 2473011417S0002
Author(s):  
Kenneth Hunt ◽  
Richard Fuld ◽  
Judas Kelley ◽  
Nicholas Anderson ◽  
Todd Baldini
Keyword(s):  
Contact Mechanics ◽  
Ankle Joint ◽  
Motion Capture ◽  
Contact Area ◽  
Subtalar Joint ◽  
Ankle Instability ◽  
Weight Bearing ◽  
Calcaneofibular Ligament ◽  
Tibiotalar Joint ◽  
Ankle Stability

Category: Ankle Introduction/Purpose: Acute inversion ankle sprains are among the most common musculoskeletal injuries. Higher grade sprains, which include anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL) injury, can be particularly problematic and often require surgical repair. The implications of CFL injury on ankle instability are unclear. We aim to evaluate the impact of CFL injury on ankle stability and subtalar joint biomechanics. We hypothesized that CFL injury will result in decreased stiffness and torque, and alteration of ankle contact mechanics compared to the uninjured ankle in a cadaveric model. Methods: Twenty matched cadaveric ankles dissected of skin and subcutaneous tissue were mounted to an Instron with 20° of ankle plantar flexion and 15° of internal rotation. Intact specimens were axially loaded to body weight, then underwent inversion stress along the anatomic axis of the ankle from 0 to 20° (simulating inversion injury) for three cycles. ATFL and CFL were sequentially sectioned, and inversion testing repeated for each condition. Stiffness and change in torque were recorded using an Instron, and pressure and contact area were recorded using a calibrated Tekscan sensor system. Inversion angle of the talus and calcaneus relative to the ankle mortise were recorded using a three-dimensional motion capture system. Paired t tests were performed for inter and intra-group comparisons. Results: Stiffness and torque did not significantly decrease after sectioning of the ATFL, but did decreased significantly after sectioning of CFL. Peak pressures in the tibiotalar joint decreased significantly following CFL release compared to both the uninjured ankle and ATFL-only release. Mean contact area significantly increased following CFL release compared to both the uninjured ankle and ATFL release. There was a concentration of force in the anteromedial ankle joint during weight-bearing inversion. However, the center-of-force shifts 1.22 mm posteromedial after CFL release relative to an intact ankle. Motion capture showed a significant and sequential increase in inversion angle of both the calcaneus and talus, after release of each ligament. There was significantly more inversion in the subtalar joint than the tibiotalar joint with weight-bearing inversion. Conclusion: There is significantly lower stiffness and torque with weight-bearing inversion of the ankle joint complex following injury to both ATFL and CFL, and sequentially greater inversion of the talus and calcaneus with progressive ligament injury. This corresponds to a significant shift in the center of force in the tibiotalar joint. CFL contributes considerably to lateral ankle stability, and sprains that include CFL injury result in substantial alteration of contact mechanics at the ankle and subtalar joints. Repair of CFL may be beneficial during lateral ligament reconstruction, potentially mitigating long-term consequences (e.g., articular damage) of a loose or incompetent CFL.

scholarly journals Osteochondral Lesions of the Talus – A Biomechanical Explanation for Larger OLT Shoulder Lesions Leading to Increased Patient Risk

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0004
Author(s):  
Peter Lawson ◽  
Pam Kumparatana ◽  
Todd Baldini ◽  
Shanthan Challa ◽  
Daniel Moon ◽  
...  
Keyword(s):  
Surface Area ◽  
Ankle Joint ◽  
Contact Area ◽  
Peak Pressure ◽  
Defect Size ◽  
Cartilage Tissue ◽  
Osteochondral Lesions ◽  
Talar Dome ◽  
Increased Risk ◽  
Donor Characteristics

Category: Ankle, Trauma Introduction/Purpose: Osteochondral lesions of the talus (OLT) are a common injury that can result in pain, disability, and risk ankle degeneration, with poor outcomes when not managed properly. Unconstrained ‘shoulder’ lesions on the medial edge of the talar dome present a particular challenge. The objective of this study was to assess the effect of increasing size of a medial OLT shoulder lesion on ankle joint contact mechanics and to determine a threshold size that would warrant bulk grafting of the defect. Our hypothesis is that larger defects will demonstrate increased pressure applied over a lesser surface area, with peak pressure progressing towards the rim of the defect, resulting in an increased risk for tissue damage and need for treatment. Methods: Nine cadaver ankle joints were dissected without disrupting the medial and lateral stabilizing ligaments. A Tekscan pressure sensor was inserted into the ankle joint. Intact specimens were axially compressed up to 800 N with the foot in neutral and again at 20° inversion, simulating ankle position during inversion injury. The specimens were then tested with progressively larger semicircular osteochondral lesions at diameters of 8, 10, 12, 14, and 16 mm that were centered on the edge of the medial talar dome, followed by a final ovoid lesion of 16x20 mm. After each lesion was created the specimens were retested. Linear mixed models adjusted for donor characteristics and assessed changes in peak pressure (MPa), contact area (mm2), peak pressure location (mm), and distance from peak pressure location to the lateral rim of the defect (mm) by defect size and ankle position. Results: For all defect sizes, mean peak pressures were significantly higher in inversion compared to neutral. Mean peak pressure magnitude progressively increased with defect size in both ankle positions. Donor characteristics did not significantly affect mean peak pressure. Contact area decreased in both positions as defect size increased, but inversion led to significantly lower contact areas than in neutral. In neutral positions, the location of peak pressure moved laterally on the talar dome but also moved closer to the defect rim as the size of the defect increased. The rim-peak pressure distance stabilized for defect sizes of 10 mm and above. In inversion, however, the rim-peak pressure distance remained unchanged at about 8 mm for all defect sizes. Conclusion: As OLT defect sizes increased, we observed an increase in peak pressure, a decrease in contact surface area, and a lateral translation of peak pressure location relative to the defect rim. Distance between location of peak pressure and defect rim decreased with neutral loading until a 10 mm defect but remained consistent in inversion loading. These findings suggest a biomechanical explanation for secondary injuries and treatment failures in larger OLT shoulder lesions due to maladaptive cartilage tissue on the dome of the talus. Larger defects (=10 mm) remain a critical point of interest with predictive clinical value for OLT outcomes.

Effect of Post-traumatic Tibiotalar Osteoarthritis on Kinematics of the Ankle Joint Complex

2009 ◽  
Vol 30 (8) ◽  
pp. 734-740 ◽  
Author(s):  
Michal Kozanek ◽  
Harry E. Rubash ◽  
Guoan Li ◽  
Richard J. de Asla
Keyword(s):  
Ankle Joint ◽  
Subtalar Joint ◽  
Imaging Techniques ◽  
Weight Bearing ◽  
Surgical Techniques ◽  
Heel Strike ◽  
Control Group ◽  
Tibiotalar Joint ◽  
Results Of Treatment ◽  
Post Traumatic

Background: Knowledge of joint kinematics in the healthy and diseased joint may be useful if surgical techniques and joint replacement designs are to be improved. To date, little is known about the kinematics of the arthritic tibiotalar joint and its effect on the kinematics of the subtalar joint. Materials and Methods: Kinematics of the ankle joint complex (AJC) were measured in six patients with unilateral post-traumatic tibiotalar osteoarthritis in simulated heel strike, midstance and toe off weight bearing positions using magnetic resonance and dual fluoroscopic imaging techniques. The kinematic data obtained was compared to a normal cohort from a previous study. Results: From heel strike to midstance, the arthritic tibiotalar joint demonstrated 2.2 ± 5.0 degrees of dorsiflexion while in the healthy controls the tibiotalar joint plantarflexed 9.1 ± 5.3 degrees ( p < 0.01). From midstance to toe off, the subtalar joint in the arthritic group dorsiflexed 3.3 ± 4.1 degrees whereas in the control group the subtalar joint plantarflexed 8.5 ± 2.9 degrees ( p < 0.01). The subtalar joint in the arthritic group rotated externally 1.2 ± 1.0 degrees and everted 3.3 ± 6.1 degrees from midstance to toe off while in the control group 12.3 ± 8.3 degrees of internal rotation and 10.7 ± 3.8 degrees eversion ( p < 0.01 and p < 0.01, respectively) was measured. Conclusion: The current study suggests that during the stance phase of gait, subtalar joint motion in the sagittal, coronal, and transverse rotational planes tends to occur in an opposite direction in subjects with tibiotalar osteoarthritis when compared to normal ankle controls. This effectively represents a breakdown in the normal motion coupling seen in healthy ankle joints. Clinical Relevance: Knowledge of ankle kinematics of arthritic joints may be helpful when designing prostheses or in assessing the results of treatment interventions.

scholarly journals Subtalar Joint Alignment in Ankle Osteoarthritis

2017 ◽  
Vol 2 (3) ◽  
pp. 2473011417S0002
Author(s):  
Nicola Krähenbühl ◽  
Lukas Zwicky ◽  
Manja Deforth ◽  
Beat Hintermann ◽  
Markus Knupp
Keyword(s):  
Ankle Joint ◽  
Subtalar Joint ◽  
Ct Scans ◽  
Control Group ◽  
Talar Dome ◽  
Ankle Arthritis ◽  
Ankle Osteoarthritis ◽  
Talar Tilt ◽  
Joint Inclination ◽  
Weightbearing Ct

Category: Ankle Arthritis, Hindfoot Introduction/Purpose: The influence of the subtalar joint on the evolution of ankle joint osteoarthritis is still a matter of debate. Although subtalar joint compensation of deformities above the ankle joint was proposed until mid-stage of ankle osteoarthritis, the evidence of this assumption is weak. In this study, we investigated the subtalar joint alignment in different stages of ankle joint osteoarthritis using weightbearing CT scans. The influence of the tibio-talar tilt and presence of subtalar joint osteoarthritis was additionally assessed. We hypothesized, that the subtalar joint compensates for deformities above the ankle joint in early- to mid-stage of ankle osteoarthritis. We also hypothesized, that subtalar joint compensation increases with a pronounced tibio-talar tilt and decreases with the presence of subtalar joint osteoarthritis. Methods: We included patients with ankle joint osteoarthritis treated in our institution from January 2013 to April 2016. A control group of 28 patients was additionally assessed. Varus and valgus ankles were subdivided according to the modified Takakura classification, the tilt of the talus in the ankle mortise and stage of subtalar joint osteoarthritis. The type of ankle osteoarthritis was diagnosed on a plain weightbearing anterior to posterior radiograph of the ankle. The medial distal tibial angle (TAS) and the angle between the tibial shaft and the surface of the talar dome (TTS) were measured. The subtalar joint alignment was assessed using weightbearing CT scans. Two angles were assessed: The subtalar inclination angle (SIA) was measured to investigate the subtalar compensation. For assessment of the morphology of the talus, the inftal-subtal angle (ISA) was determined. Results: This analysis showed significant differences of the subtalar inclination between varus feet and the controls (SIA, P=.001). Regarding the talar morphology, significant differences were found between varus/ valgus feet and the controls (ISA, P=.001 and .036, respectively). No significant differences of the subtalar joint inclination and talar morphology could be identified comparing different stages of ankle joint osteoarthritis inside the varus or valgus group. No relationship between the tilt of the talus in the ankle joint mortise and the subtalar joint inclination or talar morphology was identified. Neither presence nor absence of subtalar joint osteoarthritis influenced the subtalar joint inclination and talar morphology. Conclusion: Varus ankles compensate in the subtalar joint for deformities above the ankle joint. Compensation had no influence on the stage of ankle osteoarthritis, extent of the tibio-talar tilt and stage of subtalar joint osteoarthritis. Consequently, the progression of ankle joint osteoarthritis is more depended on the supramalleolar alignment and integrity of the periarticular structures (i.e. ligaments and tendons) than on the osseous alignment of the subtalar joint.

scholarly journals Distal Fibula Osteotomies Improve Tibiotalar Joint Compression

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0014
Author(s):  
Christopher Arena ◽  
Umur Aydogan ◽  
Evan Roush ◽  
Paul Juliano
Keyword(s):  
Ankle Joint ◽  
Contact Area ◽  
Peak Pressure ◽  
Ankle Arthrodesis ◽  
Pressure Measurements ◽  
Distal Fibula ◽  
Tibiotalar Joint ◽  
Joint Force ◽  
Oblique Osteotomy ◽  
Ankle Pressure

Category: Basic Sciences/Biologics Introduction/Purpose: Compression is a vital component of achieving a successful ankle arthrodesis. Various modifications of the fibula are used in hopes of achieving higher clinical rates of successful fusion in ankle arthrodesis procedures. We hypothesized that distal fibula osteotomies would improve tibiotalar joint compression under various loading conditions. The purpose of this study was to evaluate the effect of various distal fibula osteotomies on tibiotalar joint compression. Methods: Eight paired adult cadaveric lower extremity specimens with an intact ankle joint and syndesmosis were prepared by exposing and fixating together the proximal tibia and fibula. A jig was constructed to secure the specimen in a vertical position while allowing free axial loading. An anterior surgical approach to the ankle was performed and the joint cartilage denuded. A pressure transducer was used to record baseline ankle pressure distribution. The proximal specimen was loaded with 30, 50, and 100 N static weight and ankle pressure measurements repeated for each load. The fibula was surgically modified with the three procedures: (1) oblique fibular osteotomy 3 cm proximal to the ankle joint; (2) 1 cm long distal fibula resection; (3) complete distal fibula excision. Increasing loads of 30, 50, and 100 N following each surgical procedure were applied and the ankle pressure measurements repeated. Results: Distal fibula resection increased tibiotalar joint force, peak pressure, and contact area compared to intact fibula control for 30, 50, and 100 N loads applied (p<0.05). Compared to intact fibula control, an oblique osteotomy performed and 30 N applied force resulted in a mean ankle joint force increase of 7.5 N (p = 0.007). A 1 cm excisional fibula osteotomy under a 30 N load significantly increased the ankle joint force by 6.6 N (p = 0.015). Complete distal fibula resection under 30 N load significantly increased the ankle joint force compared to control by 13.9 N (p < 0.001). Similar trends were seen for 50 N and 100 N loads with significance reached (*) as represented in Figure 1 (error bar = standard error). Conclusion: A distal fibula oblique osteotomy, 1 cm excisional osteotomy, or complete distal fibula excision may increase the amount of force transmitted to the ankle joint under loading. Our findings suggest complete distal fibular resection results in the highest ankle joint force, contact area, and peak pressure of the surgical options tested. Leaving the fibula intact may decrease tibiotalar compression during ankle arthrodesis. Clinical testing would be important to ultimately test the effects on rates of successful fusion.

scholarly journals Ankle and Subtalar Joint Kinematics following Lateral Ligament Repair- Implications for Early Surgical Treatment

2017 ◽  
Vol 2 (3) ◽  
pp. 2473011417S0002
Author(s):  
Kenneth Hunt ◽  
Nicholas Anderson ◽  
Judas Kelley ◽  
Richard Fuld ◽  
Todd Baldini
Keyword(s):  
Motion Capture ◽  
Contact Area ◽  
Subtalar Joint ◽  
Peak Pressure ◽  
Weight Bearing ◽  
Joint Kinematics ◽  
Ligament Repair ◽  
Tibiotalar Joint ◽  
Ligament Healing ◽  
The Impact

Category: Ankle Introduction/Purpose: The current trend for chronic lateral ankle instability treatment is direct repair of the ATFL and/or CFL by open or arthroscopic-assisted technique. There is recent evidence suggesting improved success with acute ligament repair following high grade ankle sprains as well as on the impact of CFL injury on ankle and subtalar biomechanics. However, the impact of acute repair on ankle and subtalar joint kinematics and biomechanics is not well understood. The purpose of this study was to determine the impact of repairing the ATFL alone compared to repairing both the ATFL and CFL, on restoration of ankle and subtalar joint kinematics. Methods: Ten matched pairs of fresh frozen human cadaveric ankles were dissected to expose intact ATFL and CFL. Ankles were mounted to an Instron at 20° plantar flexion and 15° of internal rotation. Each ankle was loaded to body weight and then inverted from 0 to 20° for three cycles; Peak pressure and contact area were recorded in the ankle joint using a calibrated Tekscan sensor system, and linear and rotational displacement of the talus and calcaneus relative to the ankle mortise was recorded using a three-dimensional motion capture system. Ankles then underwent sequential sectioning of ATFL and CFL and were randomly assigned to ATFL-only repair using two arthroscopic Broström all-soft anchors, or combined ATFL and CFL repair. Testing was repeated after repair. Results: Motion capture showed a significant increase in inversion angle of both the calcaneus and talus after release of each ligament. There was significantly more inversion in the subtalar joint than the tibiotalar joint with weight-bearing inversion. There was a significant increased medial shift of the calcaneus after CFL release. Neither ATFL alone nor combined ATFL/CFL repairs restored normal ankle joint inversion. Isolated ATFL repair restored inversion of subtalar joint nearing the intact state. We found no significant difference in peak pressure or contact area in the tibiotalar joint between the intact ankle and ATFL or combined repair. However, there was a 26% decrease in peak pressure following ATFL repair, and only an 11% decrease in peak pressure following ATFL/CFL repair compared to the uninjured ankle. Conclusion: The addition of CFL repair does not appear to provide significant improvement compared to ATFL repair alone in the immediate repair setting. Neither group demonstrated restoration of normal talus inversion with weight-bearing inversion testing, suggesting that acute repair, without a period of ligament healing, is not sufficient to resist a weight-bearing inversion moment. While the CFL plays an important role in normal ankle mechanics, this data supports the necessity for a protection period to allow sufficient ligament-healing before weight-bearing inversion stresses are applied following surgical repair.

Measurement and Visualization of the Contact Pressure Distribution of Rubber Disks and Tires

1995 ◽  
Vol 23 (4) ◽  
pp. 238-255 ◽  
Author(s):  
E. H. Sakai
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Contact Area ◽  
Light Absorption ◽  
Lateral Force ◽  
Contact Pressure Distribution ◽  
High Definition ◽  
The Road ◽  
Close Relationship ◽  
Processing Techniques

Abstract The contact conditions of a tire with the road surface have a close relationship to various properties of the tire and are among the most important characteristics in evaluating the performance of the tire. In this research, a new measurement device was developed that allows the contact stress distribution to be quantified and visualized. The measuring principle of this device is that the light absorption at the interface between an optical prism and an evenly ground or worn rubber surface is a function of contact pressure. The light absorption can be measured at a number of points on the surface to obtain the pressure distribution. Using this device, the contact pressure distribution of a rubber disk loaded against a plate was measured. It was found that the pressure distribution was not flat but varied greatly depending upon the height and diameter of the rubber disk. The variation can be explained by a “spring” effect, a “liquid” effect, and an “edge” effect of the rubber disk. Next, the measurement and image processing techniques were applied to a loaded tire. A very high definition image was obtained that displayed the true contact area, the shape of the area, and the pressure distribution from which irregular wear was easily detected. Finally, the deformation of the contact area and changes in the pressure distribution in the tread rubber block were measured when a lateral force was applied to the loaded tire.

scholarly journals Temporary hemiepiphysiodesis using an eight‐plate implant for coronal angular deformity around the knee in children aged less than 10 years: efficacy, complications, occurrence of rebound and risk factors

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhen-Zhen Dai ◽  
Zhen-Peng Liang ◽  
Hao Li ◽  
Jing Ding ◽  
Zhen-Kai Wu ◽  
...  
Keyword(s):  
Risk Factors ◽  
Risk Factor ◽  
Deformity Correction ◽  
Genu Valgum ◽  
Angular Deformity ◽  
Screw Loosening ◽  
Logistic Regression Models ◽  
The Mean ◽  
Low Incidence ◽  
Angular Deformities

Abstract Background Temporary hemiepiphysiodesis (TH) using an eight-Plate implant is one of the most common surgeries used for the correction of coronal angular deformities around the knee in adolescents. However, few studies have focused on children aged less than 10 years treated with TH using an eight-Plate implant. The purpose of this study was to investigate the efficacy, correction velocity, and complications of TH with an eight-Plate implant as well as the occurrence of rebound and risk factors in this population. Methods This retrospective study included a total of 135 physes (101 knees) from 66 children (mean age of 4.69 years old, range from 1 to 10 years old) who underwent TH with an eight-Plate implant to correct coronal genu angular deformities in our hospital. Related clinical factors were recorded and analysed by multivariable linear and logistic regression models. Results The mean deformity correction period was 13.26 months, and the mean follow-up after eight-Plate removal was 12.71 months. In all, 94.06% (95/101 knees) of the genu angular deformities were completely corrected. Non-idiopathic genu angular deformity was found to be an independent risk factor for deformity correction failure (odds ratio (OR) = 2.47). The femoral correction velocity was significantly higher than the tibial correction velocity (1.28° vs. 0.83° per month, p < 0.001). After adjustment for other factors, younger children had higher correction velocities in the distal femur; however, genu valgum and idiopathic deformities were associated with higher correction velocities in the proximal tibia. In addition, we found three (3/101, 2.97%) knees with genu valgum that experienced rebound after removal of the eight-Plate, while five (5/101, 4.95%) knees with non-idiopathic genu angular deformity experienced screw loosening. No other complications were found, and non-idiopathic deformity was the only risk factor for complications (OR = 3.96). No risk factor was found for rebound in our study. Conclusions TH using an eight-Plate implant is an effective procedure for coronal genu angular deformities with a low incidence of complications and rebound in patients younger than 10 years old. For this population, TH using an eight-Plate should be considered as soon as the deformity stops responding to conservative treatments. The parents of children younger than 10 years of age with non-idiopathic deformities should be informed preoperatively that the deformity may be prone to correction failure or screw loosening after eight-Plate implantation.

Experimental and Theoretical Study of the Contact Mechanics of Five Total Knee Joint Replacements

1995 ◽  
Vol 209 (4) ◽  
pp. 225-231 ◽  
Author(s):  
T Stewart ◽  
Z M Jin ◽  
D Shaw ◽  
D D Auger ◽  
M Stone ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Knee Joint ◽  
Contact Pressure ◽  
Contact Stress ◽  
Linear Elasticity ◽  
Contact Area ◽  
Elasticity Analysis ◽  
Joint Replacements ◽  
Total Knee ◽  
Maximum Contact

The tibio-femoral contact area in five current popular total knee joint replacements has been measured using pressure-sensitive film under a normal load of 2.5 kN and at several angles of flexion The corresponding maximum contact pressure has been estimated from the measured contact areas and found to exceed the point at which plastic deformation is expected in the ultra-high molecular weight polyethylene (UHMWPE) component particularly at flexion angles near 90°. The measured contact area and the estimated maximum contact stress have been found to be similar in magnitude for all of the five knee joint replacements tested. A significant difference, however, has been found in maximum contact pressure predicted from linear elasticity analysis for the different knee joints. This indicates that varying amounts of plastic deformation occurred in the polyethylene component in the different knee designs. It is important to know the extent of damage as knees with large amounts of plastic deformation are more likely to suffer low cycle fatigue failure. It is therefore concluded that the measurement of contact areas alone can be misleading in the design of and deformation in total knee joint replacements. It is important to modify geometries to reduce the maximum contact stress as predicted from the linear elasticity analysis, to below the linear elastic limit of the plastic component.

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