Contact analysis of horizontal cleavage tear treatment.
Horizontal cleavage tears (HCT) commonly occur in the posterior horn of the medial meniscus due to aging and degeneration. The purpose of this study was to investigate the surgical treatment of HCTs and their effect on dynamic tibiofemoral contact mechanics. The tibiofemoral contact mechanics of 10 cadaver knees were investigated using a custom dynamic loading apparatus, pressure sensor, and motion sensing camera. Three loading conditions were analyzed: 500 N compressive load, 500 N compressive load with 100 N posterior shear, and 500 N compressive load with 2.5 Nm of internal torque. Real-time peak contact pressures and contact areas were recorded throughout the full range of motion. After testing the intact meniscal state, a horizontal cleavage tear was created and included 50% of the width of the meniscus. The following procedures were performed, and the loading conditions described above were analyzed: HCT superior flap removal (5 specimens), HCT inferior flap removal (remaining 5 specimens), and both flaps removed (all 10 specimens). Statistical analysis was performed using a mixed linear effects model using the R-statistical package. The mixed linear effects statistical model identified statistically significant differences between independent variables, including the procedure performed, meniscal flap removed, meniscal region, loading condition, and knee flexion angle with respect to contact area and peak contact pressure. Peak contact pressure and contact area were not affected by selective flap removal (superior vs. inferior) or removal of both flaps of the HCT. We recommend that in the treatment of horizontal cleavage tears of the posterior horn of the medial meniscus, the outer 50% of the posterior horn of the medial meniscus should be maintained for load transmission.
The medial meniscus of the human knee is important for load distribution to the articular cartilage and surrounding soft tissues. It is estimated that the medial meniscus is involved in distributing 60% of the knee's load. (1,2) Injury to the meniscus disrupts the normal contact mechanics of the knee by altering the distribution of stresses to the underlying articular cartilage. A deficiency in meniscal function can be caused by trauma but also by arthroscopic partial meniscectomy. Meniscectomy decreases the overall contact area and increases peak contact pressures on tibial cartilage. (3-6) Altered contact mechanics in the knee are believed to result in Fairbank changes that characterize degenerative osteoarthritis (OA): sclerosis, joint space narrowing, squaring of the tibial margin, flattening of the femoral condyles, and osteophyte formation. (7,8)
Horizontal cleavage tears (HCT) are degenerative tears often found in the posterior horn of the medial meniscus and are believed to be the result of shear force fatigue in older patients. (9,10) These lesions result in a meniscus separated into a superior and inferior flap. (10,11) HCT have been shown to be associated with an increased risk of OA. (11,12) Arno and coworkers investigated alterations in tibiofemoral contact mechanics due to HCT pathology of the posterior horn of the medial meniscus. (13) In this follow-up study, we aim to investigate the treatment of HCT lesions and their effect on tibiofemoral contact area and peak contact pressures throughout the range of motion. This study utilized the same specimens as Arno and coworkers but evaluates the surgical treatment of HCT lesions as opposed to the HCT pathology that was described. (13) We hypothesize that partial meniscectomy of either the superior or inferior flap of a horizontal cleavage tear will result in increased contact pressures on the uncovered cartilage and on the remaining posterior horn of the meniscus.
Materials and Methods
Ten fresh frozen human cadaveric knee specimens (7 male and 3 female; 3 left and 7 right) with average age of 77 years (range: 55 to 91 years) were obtained. Subcutaneous soft tissues were removed from each cadaveric specimen until the knee capsule was reached; all ligaments and the quadriceps tendon were preserved. Afterward, each specimen underwent MR imaging on a Siemens MAGNETOM Skyra 3 Tesla (3T) MRI machine (Siemens, Malvern, PA) with a 15 channel transmit and receive knee coil, including two sequences:
1. 3D-Proton Density-Non-Fat Suppressed-SPACE (Sampling Perfection with Application optimized Contrasts using different flip angle Evolutions) sequence (flip angle = 120[degrees]; repetition time (TR) = 1,000 msec; echo time (TE) = 46 msec; bandwidth = 460 Hz/pixel; Field of View (FOV) = 160 mm x 160 mm; matrix size = 320 x 300 pixels; voxel size = 0.5 x 0.5 x 0.5 mm (3) ) and
2. 3D-T2* mapping with Gradient Echo (GRE) sequence (TR = 30 msec; TE = 10 echoes (2.01 msec - 25.50 msec); flip angle = 25[degrees];, bandwidth = 450 Hz/pixel; FOV = 220 mm x 84.4 mm; matrix size = 384 x 100; voxel size = 0.6 x 0.6 x 0.6 mm (3)). These sequences were obtained to verify the integrity of the cartilage and ligaments and the meniscus, respectively.
In order to assess dynamic contact mechanics of the knee, the testing apparatus (Fig. 1) described by Arno and coworkers was implemented. (13,14) This system has three major components: a mechanical apparatus to mount the specimen and apply a full range of motion, an optical motion tracking system (MicronTracker Sx60, ClaroNav Technology Inc., Toronto, Ontario, Canada) to quantify the range of motion, and a thin (0.1 mm) pressure sensor (4,011 N, Tekscan Inc., Boston, MA) to record peak pressures and total contact area. The femur and tibia were fixed to the testing apparatus using cemented intramedullary rods and screws; the tibia was positioned vertically, and the femur was positioned such that the epicondylar axis was horizontal.
Two transverse rods were placed in the femoral frame in-line with the epicondyles. Cables were connected from the rods to the servo motors in order to apply compression, shear, and torque. Normal patellar tracking through the range of motion was accomplished by quadriceps tensioning using Krackow suturing through the quadriceps and attached via cables to the testing apparatus. Elastic bands in combination with cabling from a pneumatic cylinder were used to take each specimen through the full range of motion (-5[degrees]; to 135[degrees];, unless anatomically blocked) dynamically in 15 seconds. The MicronTracker optical motion tracking system using black and white targets on the femoral frame was used to track the specimen through the range of motion.
With the cadaveric specimen mounted in the testing apparatus, an anterior arthrotomy was carefully created under the medial and lateral menisci being sure to avoid disrupting the anterior root attachments and patellar tendon. A thin (0.1 mm) Tekscan pressure sensor was inserted below the menisci and held in place with sutures through the posterior capsule. Prior to insertion, each sensor was equilibrated, calibrated, and conditioned according to the manufacturer's recommendations. The I-Scan software (Tekscan Inc., Boston, MA) was used to record measurements from the pressure sensor throughout the range of motion.
Each medial meniscus intact specimen was taken through its full range of motion starting at full extension and pro gressing to full flexion (135[degrees];) for one cycle. During the range of motion, one of three loading conditions was applied in the following order: 500 N compressive load, 500 N compressive load with 100 N posterior shear (PS), and 500 N compressive load with 100 N of internal torque (IT). The compression-shear and compression-torque ratios used were based on the instrumented knee data from Heinlein and colleagues and D'Lima and associates. (15,16) The force combinations were performed in the same order for each specimen. Using the synchronized motion capture system and pressure sensor, the knee position and corresponding pressure and contact area data were continuously recorded through the range of motion. The intact meniscus (prior to HCT lesion) serves as a reference for the cases of superior, inferior, and both meniscal flap removal that follow.
After testing of the knees with an intact medial meniscus, a horizontal cleavage tear was created arthroscopically with a Beaver [R] Mini-Blade (Beaver-Visitec International Inc., Waltham, MA) in the posterior horn of the medial meniscus by an orthopaedic surgeon as described by Arno and coworkers (13) (Fig. 2A-C). This lesion equally divided the meniscus into superior and inferior flaps, extending 70% of the total length of the posterior horn starting 0.5 cm from the root attachment. The tear included 50% of the width of the posterior horn; the width was determined by MRI for each subject. After creation of the HCT lesion, five specimens underwent removal of the superior flap, and five specimens underwent removal of the inferior flap using standard arthroscopic instrumentation (Fig. 2D). A new pressure sensor was positioned, and the above mentioned testing protocol was repeated. Next, the remaining superior or inferior flap was removed arthroscopically using standard arthroscopic instrumentation (Fig. 2E). Again, a new pressure sensor was positioned and the testing protocol was repeated.
To verify the reproducibility of the sensors, the tests were repeated under the 500 N compression, 500 N compression with 100 N PS, and 500 N compression with 2.5 Nm IT in six intact knees. The average error between the two trials was determined for peak contact pressure and contact area.
After completion of testing, the cadaveric knee was stripped of all pericapsular soft tissues. Using a probe, the inner boundary of the medial meniscus on the sensor was mapped in the I-Scan software. Based on this map of the unloaded meniscus, four regions were defined on the pressure maps from testing: 1. Anterior region--anterior meniscal horn contained, 2. Central region--central meniscal body contained, 3. Posterior region--posterior meniscal horn contained, and 4. Uncovered cartilage--where no meniscus was contained (Fig. 3). For the three loading conditions, the peak contact pressure and total contact area were recorded in each region of the medial compartments at -5[degrees]; and then in 15[degrees]; increments from full extension to 135[degrees]; of flexion.
In order to evaluate differences of independent variables (predictors) in repeated measurements on contact area and peak contact pressure, a linear mixed-effect model was used. The statistical model was designed to evaluate contact area and peak contact pressure as a function of these independent variables within specimens. A random statement with study knees (subjects) as the random effect was included to account for the correlation within knees (subjects) because of the repeated nature of the data. Statistical analysis was conducted using the R-statistical package (www.r-project.org) using the linear and nonlinear mixed effects models (nlme) package to generate the mixed model. Statistical significance of p < 0.05 was considered to be relevant.
The pre-testing MRI using the 3D-Proton Density-Non-Fat Suppressed-SPACE sequence demonstrated that all specimens contained fully intact ligamentous structures. The T2* mapping with Gradient Echo (GRE) sequence which was confirmed at the time of arthroscopy demonstrated fibrillation in three menisci, and mild intra-substance degeneration was present in the remaining seven menisci. The region of greatest meniscal degeneration was the posterior horn.
The pressure sensor reliability study indicated that the average discrepancy between trials was 18.43 [+ or -] 15.47 KPa for peak contact pressure and 0.02 [+ or -] 0.02 cm (2) for contact area. Tables 1 and 2 provide peak contact pressure and contact area averaged for all knees and angles for each loading condition, respectively. Figure 4 demonstrates one example of the pressure map of the medial portion of the tibial plateau with the pre-defined meniscal regions.
The mixed linear effects statistical model identified statistically significant differences between independent variables, including the procedure performed, portion of meniscus removed, meniscal region, loading condition, and angle with respect to contact area (Table 3) and peak contact pressure (Table 4). With regard to the performed procedure, there was a difference in contact area but not peak pressure between the intact state, HCT flap removed state, and both HCT flaps removed (all p < 0.001). With respect to the portion of the meniscus that was removed, there was no significant difference between the superior and inferior flap being removed with regard to contact area and peak contact pressure. There was, however, a difference between removal of the inferior flap and the intact state, removal of the superior flap and the intact state, and removal of both flaps and the intact state with regard to contact area but not peak contact pressure (all p < 0.001).
With regard to the meniscal region, there was statistically significant differences between each of the regions and the anterior horn of the meniscus both with regard to contact area and peak contact pressure (all p < 0.001). With regard to loading condition, there was no significant difference between compression and compression with IT; however, there was significant difference between compression versus compression with PS and compression with PS versus compression with IT with regard to contact area (p < 0.001, p < 0.006) and peak contact pressure (p < 0.015, p < 0.019). With regard to angle of the arc of motion, there was statistically significant differences identified in both contact area and peak contact pressure throughout the arc of motion and also between multiple positions with respect to full extension.
The arthroscopic treatment of horizontal cleavage tears is common as these degenerative tears comprise at least 50% of all meniscal tears and are correlated with chondral defects and other traumatic tears. (11,12,17) The postoperative contact mechanics of the treatment of HCT has not been previously reported to our knowledge. Herein, we suggest that treatment of HCTs alter the contact area and peak contact pressure of the medial meniscus, but treatment with selective flap removal is not statistically different from removal of both HCT flaps when 50% of the width of the posterior horn of the medial meniscus is involved.
With regard to contact area, our data shows a trend toward decreasing contact area in the posterior horn with progressive removal of the HCT lesion in all three loading conditions and procedures; this change was expected and correlated with arthroscopic removal of the meniscal flap during the procedure and resulted in statistically significant differences in nearly all conditions that were tested. On closer examination of the mean contact area values shown in Table 1, it should be noted that the anterior horn, central body, and uncovered cartilage regions show relatively stable contact areas especially when considering the associated standard deviations. The statistical comparison between contact area between the superior and inferior HCT flap removal demonstrated no significant difference between the procedures. Given the inner 50% of the meniscus was involved in our HCT lesion, our results suggest that the outer (peripheral) 50% of the meniscus carries the bulk of the load with regard to contact area throughout the dynamic range of motion and the tested loading conditions.
With regard to peak pressure, there was no significant difference in peak pressures between the removal of the superior and inferior HCT flap. There was also no significant difference between removal of a single flap and both flaps with regard to peak contact pressures. This further supports our assertion that the outer 50% of the meniscus carries the bulk of the load throughout the dynamic range of motion and the tested loading conditions.
Arno and colleagues is the only published study that the investigators are aware of that has investigated contact mechanics of HCT of the posterior horn of the medial meniscus. (13) This study demonstrated small increases in peak contact pressure and decreases in contact area in this pathology. They suggest that these subtle alterations in joint mechanics may be a factor in cartilage degeneration and progression of osteoarthritis changes over many years.
Kim and colleagues performed a clinical outcome study on patients who underwent partial meniscectomy, horizontal cleavage tear flap removal, or subtotal meniscectomy for HCT. (18) This study investigated 312 patients with clinical function scores with a follow-up of 5 years; they also evaluated radiographs of these patients. They demonstrated that horizontal cleavage lesion flap removal resulted in the least amount of joint space narrowing in comparison to the other procedures. Furthermore, they demonstrated no statistically significant differences in functional outcome scores between partial meniscectomy and HCT flap removal but inferior scores for subtotal meniscectomy.
Our study has demonstrated statistically significant differences in peak contact pressure and contact area with regard to loading condition, contact region, and performed procedure. Our results suggest that the outer 50% of the posterior horn of the medial meniscus supports the majority of the load as inferior HCT, superior HCT, and both HCT flap removal did not result in statistically significant differences in contact area and peak contact pressure. This study did not investigate the effect of flap removal on joint stability; however, others have found that resection of greater than 46% of the posterior horn of the medial meniscus results in increased joint laxity. (14)
Changes in contact area and contact pressure after partial meniscectomy affect joint function but may take many years to develop measureable osteoarthritic changes. Kim and colleagues has described that functionally no differences may be seen in the first 5 years. (18) This study finds no difference in removal of the inner 50% of the inferior flap, superior flap, or both HCT flaps with regard to contact area and peak contact pressure. This study did not evaluate the outer 50% of the posterior horn of the medial meniscus, which is a limitation. Other limitations of this study are inherent to the use cadaveric tissues and small sample size.
Horizontal cleavage tears (HCT) are degenerative tears often found in the posterior horn of the medial meniscus and have been shown to be associated with an increased risk of OA. We have demonstrated that statistically significant changes to peak contact pressure and contact area are associated with treatment of HCT lesions in comparison to the intact meniscus. In this study, peak contact pressure and contact area were not statistically different between selective flap removal (superior vs. inferior) and removal of both flaps. When making intraoperative decisions, at least the outer 50% of the posterior horn of the medial meniscus should be maintained for load transmission. This raises important clinical questions about the role of horizontal cleavage meniscal repair versus subtotal meniscectomy.
We thank Daniel Hennessy, Daniel F. Martinez, and Michael Lowry for their contributions to the design and construction of the testing apparatus.
None of the authors have a financial or proprietary interest in the subject matter or materials discussed, including, but not limited to, employment, consultancies, stock ownership, honoraria, and paid expert testimony.
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Caption: Figure 1 Dynamic knee contact mechanics testing rig with knee in full extension (left) and 135[degrees] of flexion (right).
Caption: Figure 2 Arthroscopic images of the posterior horn of the medial meniscus demonstrating A, an intact meniscus, B, a pediatric Beaver [R] blade creating a HCT, C, an HCT, D, the superior flap of the HCT removed, and E, both flaps of the HCT lesion removed. To view this figure in color, see www.hjdbulletin.org.
Caption: Figure 3 The Tekscan sensor was divided into four regions based on the unloaded position of the meniscus on the tibial plateau measured directly after dissection of each specimen: anterior, central, and posterior meniscus portions, and uncovered cartilage on the tibial plateau. To view this figure in color, see www.hjdbulletin.org.
Caption: Figure 4 Tekscan peak contact pressure maps following application of 500 N compression from one knee at full extension (top row), 60[degrees] flexion (middle row), and 120[degrees] flexion (bottom row) for the cases of the intact (left column), HCT flap removed (middle column), and both HCT flaps removed (right column) cases of the posterior horn of the medial meniscus. To view this figure in color, see www.hjdbulletin.org.
Carlos A. Uquillas, M.D., Sally Arno, Ph.D., Austin J. Ramme, M.D., Ph.D., Cheongeun Oh, Ph.D., Peter S. Walker, Ph.D., and Robert J. Meislin, M.D.
Carlos A. Uquillas, M.D., Sally Arno, Ph.D., Austin J. Ramme, M.D., Ph.D., Peter S. Walker, Ph.D., and Robert J. Meislin, M.D., Department of Orthopaedic Surgery, New York University Hospital for Joint Diseases, New York, New York. Cheongeun Oh, Ph.D., Department of Environmental Medicine, NYU School of Medicine, New York, New York
Correspondence: Robert J. Meislin, M.D., Department of Orthopaedic Surgery, NYU Langone CMC, 333 East 38th Street, 4th Floor, New York, New York 10016; email@example.com.
Table 1 Overall Mean (Standard Deviation) of the Contact Area for Each Loading Condition, Meniscus State, and Meniscal Region Across the Arc of Motion Region Loading Condition MCA Intact Knee MCA Superior (cm(2)) HCT Flap Removed (cm(2)) Anterior Horn Comp 0.64 (0.59) 0.72 (0.52) Central Body Comp 0.93 (0.26) 0.87 (0.31) Posterior Horn Comp 1.17 (0.67) 1.65 (0.60) Uncovered Cartilage Comp 1.17 (0.68) 1.01 (0.72) Anterior Horn Comp + PS 0.72 (0.58) 0.72 (0.53) Central Body Comp + PS 0.92 (0.29) 0.86 (0.31) Posterior Horn Comp + PS 1.59 (0.65) 1.62 (0.55) Uncovered Cartilage Comp + PS 0.98 (0.65) 0.87 (0.71) Anterior Horn Comp + IT 0.82 (0.71) 0.86 (0.61) Central Body Comp + IT 0.92 (0.31) 0.92 (0.30) Posterior Horn Comp + IT 1.57 (0.68) 1.63 (0.55) Uncovered Cartilage Comp + IT 1.10 (0.63) 1.02 (0.66) Region MCA Inferior HCT MCA Both HCT Flap Removed Flaps Removed (cm(2)) (cm(2)) Anterior Horn 0.64 (0.60) 0.63 (0.57) Central Body 0.93 (0.36) 0.92 (0.30) Posterior Horn 1.17 (0.71) 1.36 (0.68) Uncovered Cartilage 1.17 (0.67) 1.01 (0.67) Anterior Horn 0.57 (0.55) 0.60 (0.53) Central Body 0.84 (0.33) 0.86 (0.31) Posterior Horn 1.30 (0.78) 1.33 (0.70) Uncovered Cartilage 0.99 (0.68) 0.85 (0.62) Anterior Horn 0.64 (0.59) 0.66 (0.62) Central Body 0.86 (0.35) 0.89 (0.37) Posterior Horn 1.31 (0.79) 1.33 (0.65) Uncovered Cartilage 1.09 (0.57) 0.89 (0.57) MCA = mean contact area, Comp = 500 N compression, Comp + PS = 500 N compression and 100 N posterior shear, Comp + IT = 500 N compression and 2.5 Nm internal torque. Table 2 Overall Mean (Standard Deviation) of the Peak Contact Pressure for each Loading Condition, Meniscus State, and Meniscal Region Across the Arc of Motion Region Loading MPCP Intact Knee MPCP Superior HCT Condition (KPa) Flap Removed (KPa) Anterior Horn Comp 317.36 (422.50) 401.13 (513.31) Central Body Comp 734.32 (500.66) 838.94 (539.51) Posterior Horn Comp 1,042.28 (809.09) 1,069.67 (642.62) Uncovered Cartilage Comp 1,192.38 (891.95) 1,000.48 (810.85) Anterior Horn Comp + PS 281.06 (351.04) 346.36 (420.38) Central Body Comp + PS 639.65 (528.96) 715.96 (581.21) Posterior Horn Comp + PS 1,262.94 (964.85) 1,221.35 (594.79) Uncovered Cartilage Comp + PS 1,032.29 (723.10) 921.39 (818.87) Anterior Horn Comp + IT 423.95 (526.83) 542.27 (622.75) Central Body Comp + IT 614.81 (608.31) 678.29 (558.62) Posterior Horn Comp + IT 1,030.29 (717.53) 1,217.56 (693.12) Uncovered Cartilage Comp + IT 1,260.20 (899.23) 1,203.17 (778.79) Region MPCP Inferior HCT MPCP Both HCT Flap Removed (KPa) Flaps Removed (KPa) Anterior Horn 245.09 (362.29) 279.41 (382.12) Central Body 1,169.42 (1,522.94) 923.44 (851.07) Posterior Horn 1,056.64 (1,205.37) 1,148.16 (1,143.22) Uncovered Cartilage 1,658.48 (1,488.35) 1,198.62 (963.87) Anterior Horn 202.64 (251.69) 252.29 (354.42) Central Body 781.46 (801.31) 788.89 (770.48) Posterior Horn 1,289.60 (1,230.24) 1,253.28 (1,213.17) Uncovered Cartilage 1,026.25 (821.72) 1,148.26 (1,240.37) Anterior Horn 251.95 (314.12) 370.73 (491.60) Central Body 704.74 (953.04) 932.57 (1,165.67) Posterior Horn 1,116.53 (1,036.92) 1,310.29 (971.14) Uncovered Cartilage 1,416.99 (1,358.39) 1,087.76 (839.05) MPCP = mean peak contact pressure, Comp = 500 N compression, Comp + PS = 500 N compression and 100 N posterior shear, Comp + IT = 500 N compression and 2.5 Nm internal torque. Table 3 Mixed Linear Model on Contact Area Demonstrating Independent Variables, Comparisons, and the Corresponding Statistical Coefficient and P-value Independent Comparison Coefficient P-value Variable (SD) Procedure HCT Flap Removed vs. -0.07 (0.02) < 0.001 Intact Both HCT Flaps Removed -0.14 (0.02) < 0.001 vs. Intact HCT Flap Removed vs. Both 0.07 (0.02) < 0.001 HCT Flaps Removed Removed Meniscus Both Flaps vs. Intact -0.14 (0.02) < 0.001 Inferior Flap vs. Intact -0.07 (0.02) 0.007 Superior Flap vs. Intact -0.06 (0.02) 0.005 Superior Flap vs. Inferior 0.08 (0.16) 0.593 Flap Region Central Body vs. Anterior 0.24 (0.02) < 0.001 Horn Posterior Horn vs. Anterior 0.76 (0.02) < 0.001 Horn Uncovered Cartilage vs. 0.31 (0.02) < 0.001 Anterior Horn Loading Condition Comp + IT vs. Comp -0.01 (0.02) 0.518 Comp + PS vs. Comp -0.06 (0.02) 0.001 Comp + PS vs. Comp + IT -0.05 (0.02) 0.006 Angle All Measured Angles -0.04 (0.003 < 0.0001 -5[degrees] vs. 0[degrees] 0.04 (0.04) 0.234 15[degrees] vs. 0[degrees] -0.11 (0.03) 0.001 30[degrees] vs. 0[degrees] -0.19 (0.03) < 0.001 45[degrees] vs. 0[degrees] -0.22 (0.03) < 0.001 60[degrees] vs. 0[degrees] -0.24 (0.03) < 0.001 75[degrees] vs. 0[degrees] -0.26 (0.03) < 0.001 90[degrees] vs. 0[degrees] -0.28 (0.03) < 0.001 105[degrees] vs. 0[degrees] -0.31 (0.03) < 0.001 120[degrees] vs. 0[degrees] -0.35 (0.03) < 0.001 135[degrees] vs. 0[degrees] -0.38 (0.03) < 0.001 Table 4 Mixed Linear Model on Peak Contact Pressure Demonstrating Independent Variables, Comparisons, and the Corresponding Statistical Coefficient and P-value Independe Comparison Coefficient P-value Variable (SD) Procedure HCT Flap Removed vs. 25.66 (26.13) 0.326 Intact Both HCT Flaps Removed 43.46 (26.10) 0.096 vs. Intact HCT Flap Removed vs. 17.93 (27.30) 0.512 Both HCT Flaps Removed Removed Both Flaps vs. Intact 43.42 (26.13) 0.097 Meniscus Inferior Flap vs. Intact 18.71 (35.80) 0.602 Superior Flap vs. Intact 31.47 (33.20) 0.344 Superior Flap vs. Inferior -44.05 (134.3) 0.743 Flap Region Central Body vs. Anterior 471.98 (28.20) < 0.001 Horn Posterior Horn vs. Anterior 844.46 (27.40) < 0.001 Horn Uncovered Cartilage vs. 839.99 (27.40) < 0.001 Anterior Horn Loading Comp + IT vs. Comp -3.08 (26.16) 0.906 Condition Comp + PS vs. Comp -63.18 (26.1) 0.015 Comp + PS vs. Comp + IT -59.61 (25.4) 0.019 Angle All Measured Angles 10.20 (3.70) < 0.0001 -5[degrees] vs. 0[degrees] 63.80 (54.30) 0.240 15[degrees] vs. 0[degrees] 33.49 (48.10) 0.486 30[degrees] vs. 0[degrees] 27.30 (48.10) 0.570 45[degrees] vs. 0[degrees] 50.07 (48.10) 0.298 60[degrees] vs. 0[degrees] 98.60 (48.10) 0.040 75[degrees] vs. 0[degrees] 134.50 (48.10) 0.005 90[degrees] vs. 0[degrees] 159.80 (48.10) < 0.001 105[degrees] vs. 0[degrees] 128.40 (48.10) 0.008 120[degrees] vs. 0[degrees] 88.30 (48.60) 0.070 135[degrees] vs. 0[degrees] 22.74 (57.10) 0.691
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|Author:||Uquillas, Carlos A.; Arno, Sally; Ramme, Austin J.; Oh, Cheongeun; Walker, Peter S.; Meislin, Robert|
|Publication:||Bulletin of the NYU Hospital for Joint Diseases|
|Date:||Jul 1, 2017|
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