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 Effect of Achilles Tendon Loading on Ankle Joint Contact Area and Peak Pressure

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0030
Author(s):  
L. Daniel Latt ◽  
Alfonso Ayala ◽  
Samuel Kim ◽  
Jesus Lopez
Keyword(s):  
Achilles Tendon ◽  
Ankle Joint ◽  
Contact Area ◽  
Axial Load ◽  
Peak Pressure ◽  
The Body ◽  
Neutral Position ◽  
Joint Contact ◽  
Axially Loaded ◽  
The Impact

Category: Ankle Introduction/Purpose: Increased tibiotalar peak pressure (PP) and decreased contact area (CA) following ankle fracture are associated with the development of post-traumatic osteoarthtritis. Lateral talar translation of just 1 mm has been shown to decrease CA by 42%. The impact of talar malalignment in other directions on ankle joint contact pressures (AJCP) are not well understood. The majority of research on AJCP has utilized cadaveric models in which body weight is simulated with an axial load applied through the tibia. This model does not account for Achilles tendon - which transmits the largest tendon force in the body during weight bearing. This study aimed to determine the effects of Achilles tendon loading on tibiotalar CA and PP in an axially loaded cadaver model at different ankle flexion angles. Methods: Ten fresh frozen cadaveric lower extremity specimens transected mid-tibia were dissected free of soft tissues surrounding the ankle, sparing the ligaments. The proximal tibia and fibula were potted in quick drying cement for rigid mounting on a MTS machine. A pressure sensing element (TekScan KScan model 5033) was inserted into the tibiotalar joint and used to measure CA (cm2) and PP (MPa). An axial load of 686 N was applied through the tibia and fibula, followed by a 350 N load via the Achilles tendon to simulate mid-stance conditions. Measurements were taken at neutral position, 15 degrees of dorsiflexion and 15 degrees of plantarflexion, with and without Achilles load. The effects of Achilles load and ankle flexion angle on CA and PP were analyzed using a 2x3 ANOVA. Bonferroni post-hoc adjustments were used for multiple comparisons. Level of statistical significance was set at p < 0.05. Results: ANOVA revealed significant main effects of ankle flexion on contact area and peak pressures (Table 1). Contact area was significantly lower for 15 degrees of plantarflexion than neutral and 15 degrees of dorsiflexion (p < 0.001). In addition, peak pressure was significantly higher for 15 degrees of plantarflexion than neutral and 15 degrees of dorsiflexion. ANOVA also indicated that contact area and peak pressure were significantly higher with Achilles load than without (p < 0.001). No interaction effects were found. Conclusion: The applied Achilles tendon load significantly altered tibiotalar PP in an axially loaded cadaver model. On the other hand, changes in CA with Achilles load were found to be minimal (~1.8%). We also found that the greatest PP and smallest CA occured during plantar flexion. This observation can be explained by a difference in width between the anterior and posterior talus. While the results of this study demonstrate the importance of Achilles tendon load on tibiotalar measurements, further studies investigating the effects of additional factors such as loading techniques are warranted to improve the physiological accuracy of cadaver models.

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 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 The Effects of Fibular Malrotation on Tibiotalar Contact Area and Peak Pressure Distributions in Weber B Ankle Fractures

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0028
Author(s):  
Ansab M. Khwaja ◽  
Alfonso E. Ayala ◽  
Brianna Goodison ◽  
Jared Irwin ◽  
L. Daniel Latt
Keyword(s):  
Contact Area ◽  
Soft Tissues ◽  
Peak Pressure ◽  
Ankle Fractures ◽  
Sensing Element ◽  
Tibiotalar Joint ◽  
Pressure Distributions ◽  
Joint Contact ◽  
Fresh Frozen ◽  
Fixed State

Category: Basic Sciences/Biologics; Ankle; Hindfoot; Trauma Introduction/Purpose: Decreased tibiotalar joint contact area (CA) and increased peak pressure (PP) following rotational ankle fractures may predispose the development of post-traumatic osteoarthritis. Previous studies have highlighted the effects of lateral talar translation on tibiotalar joint congruity. However, debate remains regarding surgical indications in minimally displaced (< 2mm of clear space widening), but potentially malrotated ankle fractures. Malrotation of the talus and fibula are poorly visualized on plain radiographs, thus their impact on ankle joint contact mechanics has not been determined. The aim of this project is to understand the effects of fibular malrotation on tibiotalar joint CA and PP distributions using an axially loaded cadaveric model. We hypothesized that fibular malrotation would result in decreased contact area and increased peak pressures within the tibiotalar joint. Methods: Ten fresh frozen cadaveric lower extremity specimens transected mid-tibia were dissected free of soft tissues surrounding the ankle, sparing the ligaments. The proximal tibia and fibula were potted in quick drying cement for rigid mounting on a MTS machine. A pressure sensing element (TekScan model 5033) was inserted into the tibiotalar joint and used to measure CA (cm2) and PP (MPa). An axial load of 686 N was applied through the tibia and fibula, followed by a 147 N load via the Achillies tendon at mid-stance position, 15o dorsiflexion and 15o plantarflexion. The samples were first tested in the native condition, a Weber B ankle fracture was simulated and then re-tested in an anatomically fixed state, and a malrotated state. Malrotation was achieved by externally rotating the talus and shortening the fibula along the fracture by the maximal amount that would allow bony apposition along the fracture line (usually 5-10mm). Results: In the six ankles tested thus far (Figure 1), we have observed small but statistically insignificant (P>0.05) increases in tibiotalar CA at all stance phases following malreduction. Significant (p>0.05) increases in tibiotalar PP were seen mid-stance following a simulated Weber B fracture, and these changes were shown to be greatest in the malreduced state versus the anatomically fixed state (7.21 MPa vs. 6.35 MPa respectively, p = 0.004). Interestingly, similar (p=0.84) decreases tibiotalar PP were shown during plantarflexion following a simulated Weber B fracture fixed in both the anatomically fixed and malreduced state. Conclusion: Our preliminary data supports the notion that significant changes in tibiotalar PP occur following ankle fractures even in an anatomically fixed state. Increases in tibiotalar PP seem to be further amplified following malreduction at specific stance phases. Further data collection is needed to validate these findings, and to determine the role of malrotation as a potential surgical indication for minimally laterally displaced ankle fractures.

scholarly journals Ankle Joint Pressure in Supination-External Rotation Injuries: A Dynamic Biomechanic Cadaveric Study

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0030
Author(s):  
Fabian Krause ◽  
Ivan Zderic ◽  
Angela Seidel ◽  
Boyko Gueorguiev ◽  
Marc C. Attinger ◽  
...  
Keyword(s):  
Operative Treatment ◽  
Contact Area ◽  
Peak Pressure ◽  
External Rotation ◽  
Clinical Results ◽  
Deltoid Ligament ◽  
Type Ii ◽  
Type Iv ◽  
Joint Contact ◽  
Supination External Rotation

Category: Ankle; Basic Sciences/Biologics; Trauma Introduction/Purpose: In isolated lateral malleolar fractures of the supination-external rotation (SER) type and competent medial stabilizers (type II and III), non-operative treatment has yielded excellent outcome. With complete rupture of the deltoid ligament (SER type IV) fracture instability increases substantially. The rationale for operative treatment of SER type IV fractures is based upon good clinical results and previous biomechanical studies. A significant reduction of the ankle contact area that however is caused by an artificially forced lateralization of the talus in the ankle mortise has been demonstrated. Presumed resultant elevated joint contact stresses are thought to lead to ankle arthritis in the longterm. Methods: In 12 lower leg specimen SER type injuries were simulated by gradual bony and ligamentous destabilization of the ankle from lateral to medial according to the mechanism of injury as described by Lauge and Hansen. High-resolution pressure sensors placed in the ankle joint recorded tibio-talar pressure changes at physiologic weightbearing (700N) in three positions (plantigrade, 10° dorsiflexion and 20° plantarflexion). Results: With increasing instability changes of the ankle kinematics were seen in SER II and III fractures with the same trend also in SER IV lesions. In the plantigrade position, the medial clear space (MCS) increased significantly from an average of 2.5+-0.4mm (no fracture) to 3.9+-1.1mm (SER type IV fracture). However, the corresponding peak pressure increased only slightly from 2.6+- 0.5 mPa to 3.0+-1.4 mPa on average, and the contact area decreased slightly from 810+-42 mm2 to 735+-27mm2 on average representing a non-significant reduction of only 9% of the contact area (p=0.08) after the deep deltoid ligament was completely dissected.The comparison of the results in plantigrade and plantarflexed position revealed substantial differences for MCS, contact area and center of force. Conclusion: Under physiologic load SER type IV isolated lateral malleolar fracture with completely disrupted deep deltoid ligament led to a significant increase of the MCS, but neither to a significant decrease of the of the joint contact area nor significant increase of peak pressure. Clinical Relevance: The findings of this biomechanical study support the recently reported good clinical results of non-operative treatment of SER type II to IV fractures.

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.

Labral Reconstruction With Iliotibial Band Autografts and Semitendinosus Allografts Improves Hip Joint Contact Area and Contact Pressure

2014 ◽  
Vol 43 (1) ◽  
pp. 98-104 ◽  
Author(s):  
Simon Lee ◽  
Thomas H. Wuerz ◽  
Elizabeth Shewman ◽  
Frank M. McCormick ◽  
Michael J. Salata ◽  
...  
Keyword(s):  
Contact Pressure ◽  
Hip Joint ◽  
Contact Area ◽  
Iliotibial Band ◽  
Joint Contact

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.

1303 In Vivo Estimation of Human Tibiotalar Joint Contact Area Using MRI

2010 ◽  
Vol 2010 (0) ◽  
pp. 354-355
Author(s):  
Makoto SAKAMOTO ◽  
Keisuke SASAGAWA ◽  
Yuji TANABE ◽  
Koichi KOBAYASHI
Keyword(s):  
Contact Area ◽  
Tibiotalar Joint ◽  
Joint Contact

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.

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