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Purpose: To confirm whether posterior displacement of the detached meniscocapsular structure in ramp lesions could be observed on magnetic resonance imaging (MRI) in the flexed knee position and to clarify whether this displacement on MRI is related to greater anterior knee laxity., Methods: This retrospective comparative trial study included 50 patients with anterior cruciate ligament injuries in whom attendant ramp lesions were observed on preoperative MRI. All patients underwent 3-T MRI at 120° of knee flexion preoperatively. The gap distance of the ramp lesion on sagittal slices was measured, and a distance greater than 1 mm was classified as gap positive. Additionally, joint effusion in the posteromedial recess was quantitatively evaluated by measuring the surface area of joint fluid. Prior to surgery, the side-to-side difference in anterior tibial translation (ATT) on stress radiographs at 20° of knee flexion was measured to evaluate anterior knee laxity. During anterior cruciate ligament reconstruction, the length of the ramp lesion was measured by a scale from the posteromedial portal., Results: Of the 50 knees, 29 had ramp lesion gaps greater than 1 mm on MRI at knee flexion. The gap-positive group had a significantly greater side-to-side difference in ATT (9.6 ± 3.6 mm vs 5.0 ± 2.7 mm, P < .001) and significantly larger ramp lesion length (15.7 ± 4.9 mm vs 11.7 ± 3.9 mm, P = .002) than the gap-negative group. The gap-positive group also had a significantly greater amount of joint effusion than the gap-negative group (P < .001)., Conclusions: Posterior displacement of the detached meniscocapsular structure in ramp lesions can be observed on MRI at knee flexion and is related to greater anterior knee laxity, lesion size, and joint effusion., Level of Evidence: Level III, retrospective comparative trial., (Copyright © 2023 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate whether the sagittal inclination angle (SIA) of a graft is associated with postoperative knee stability after anatomic anterior cruciate ligament (ACL) reconstruction., Methods: All patients who had undergone anatomic ACL reconstruction between April 2014 and September 2015 in addition to volunteers with no history of knee injury were eligible for inclusion in this study. The patients were evaluated by magnetic resonance imaging of the knee in full extension at 1 year after surgery, as were volunteers. The posterior tibial slope (PTS) angle and the SIA of the intact ACL and reconstructed graft were measured relative to each medial and lateral tibial plateau. The patients were examined for knee stability by the side-to-side difference in the anterior tibial translation on stress radiographs at minimum 2-year follow-up., Results: We included 43 patients (26 male, 17 female, mean age 32.8 ± 14.8 years) and 12 volunteers (7 male, 5 female, mean age 28.7 ± 3.1 years) as normal controls. The mean follow-up duration was 29.8 ± 3.6 months. The mean PTS angle and mean SIA in the patients did not significantly differ from those of the intact ACL. The PTS angle in the patients was not significantly correlated with postoperative side-to-side difference in the anterior tibial translation. However, the graft SIA was significantly correlated with the postoperative anterior tibial translation (medial SIA; r = 0.42, P = .005, lateral SIA; r = 0.52, P < .001)., Conclusions: Even if anatomically reconstructed, the graft SIA in reference to the tibial plateau at full knee extension is variable and is associated with postoperative knee stability. The larger graft SIA was correlated with graft laxity after anatomic ACL reconstruction., Level of Evidence: Level III, retrospective comparative study., (Copyright © 2021 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: To prospectively evaluate the sensitivity and specificity of magnetic resonance imaging (MRI) for diagnosing ramp lesions, to compare them between 1.5- and 3-T MRI, and to evaluate whether bone contusion of the posterior lip of the medial tibial plateau was associated with ramp lesions., Methods: For 155 knees that underwent primary ACL reconstruction, we prospectively examined for ramp lesions and medial meniscal body tears on MRI. MRI diagnosis of ramp lesions required high signal irregularity of the capsular margin or separation in the meniscocapsular junction of the medial meniscus posterior horn on sagittal images. Bone contusion of the posterior lip of the medial tibial plateau was verified in 105 knees with MRI performed within 6 weeks after injury. All ramp lesions were identified by transcondylar observation during surgery. The sensitivity and specificity of MRI for ramp lesions and body tears were measured. Furthermore, we evaluated whether bone contusion of the medial tibial plateau was associated with ramp lesions. The χ-square test was used for statistical analysis., Results: During surgery, ramp lesions were observed in 46 knees and medial meniscal body tears were seen in 35 knees. The sensitivity of MRI for ramp lesions was 71.7% and specificity was 90.5%. The sensitivity for ramp lesions was significantly lower than that for meniscal body tears (94.3%) (P = .01). The sensitivity of 3-T MRI (83.3%) was superior to that of 1.5-T MRI (67.6%), but not significantly different. The incidence of bone contusions was not significantly different among ramp lesions (38.5%), body tears (40.0%), or no tears (30.5%)., Conclusions: The sensitivity of MRI for diagnosing ramp lesions was significantly lower than that for medial meniscal body tears. Bone contusion of the posterior lip of the medial tibial plateau on MRI was not associated with ramp lesions., Level of Evidence: Level III, comparative trial., (Copyright © 2018 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: The aim of this study was to compare postoperative outcomes after anatomic double-bundle anterior cruciate ligament reconstruction (ACLR) in extreme knee hyperextension versus normal to mild knee hyperextension., Methods: For 100 patients who underwent anatomic double-bundle ACLR using semitendinosus tendon, we evaluated the side-to-side difference (SSD) in anterior tibial translation (measured on stress radiographs) and rotational stability (assessed by the pivot-shift test) 2 years after surgery. Loss of extension (LOE) was evaluated on lateral radiographs of both knees in full extension, and graft integrity was assessed during second-look arthroscopy 1 to 2 years after surgery. In accordance with the Beighton and Honan criteria, patients with an extension angle less than or equal to 10° in the contralateral uninjured knee composed the group with 10° or less hyperextension (N group), and those with an extension angle of greater than 10° composed the group with more than 10° hyperextension (H group). Postoperative results were compared between these groups., Results: Mean extension angles in the N and H groups were 5.8° ± 2.9° and 14.7° ± 3.0°, respectively. The mean SSD in anterior translation was 2.2 ± 2.9 mm for the N group and 2.8 ± 2.9 mm for the H group, with no significant difference. The positive ratios on the pivot-shift test were not significantly different between the groups. Mean LOE in the N and H groups was -0.7° ± 3.7° and 1.3° ± 3.3°, respectively, with a significant difference (P = .007). During second-look arthroscopy, 6 of 58 knees in the N group and 13 of 42 knees in the H group had superficial graft laceration of the anteromedial bundle graft, with a significant difference (P = .01) seen between groups., Conclusions: Anatomic double-bundle ACLR for extreme knee hyperextension may attain the same postoperative anterior and rotational stability as seen in knees with normal to mild hyperextension. However, it increased superficial graft laceration., Level of Evidence: Level III, retrospective comparative study., (Copyright © 2015 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: The purposes of this study were to measure the anterior edge of the tibial tunnel after anatomic anterior cruciate ligament (ACL) reconstruction on lateral radiographs and to determine whether the difference in tibial tunnel placement affects postoperative outcomes., Methods: For 60 patients who underwent anatomic double-bundle ACL reconstruction with semitendinosus tendon, we evaluated the side-to-side difference in anterior tibial translation on stress radiographs, as well as rotational stability by the pivot-shift test, 2 years after surgery. Loss of extension (LOE) was evaluated on lateral radiographs of both knees in full extension, and graft integrity was assessed during second-look arthroscopy 1 to 2 years after surgery. On true lateral radiographs, we measured the anterior placement percentage of the tibial tunnel using the method described by Amis and Jakob. The cutoff value was set at 25% of the mean value of the anterior edge of the ACL that Amis and Jakob reported, and patients were divided into 2 groups (27 in the anterior group and 33 in the posterior group). Postoperative clinical results were compared between the groups., Results: The mean anterior placement percentage was 26.0% ± 4.1%. The postoperative mean side-to-side difference was 1.4 ± 2.7 mm for the anterior group and 3.0 ± 2.7 mm for the posterior group, a significant difference (P < .05). The positive ratio of the pivot-shift test was not significantly different between groups (P > .05). Mean LOE in the anterior and posterior groups was 0.9° ± 3.0° and -0.8° ± 4.0°, respectively; the difference was not significant (P > .05). Five of 27 knees in the anterior group and 5 of 33 knees in the posterior group had superficial graft laceration or elongation, which was not significantly different (P > .05)., Conclusions: Anterior placement of the tibial tunnel in anatomic double-bundle ACL reconstruction leads to better anterior knee stability than posterior placement does. Anterior tibial tunnel placement inside the footprint did not increase the incidence of LOE and graft failure., Level of Evidence: Level IV, therapeutic case series., (Copyright © 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: Our purpose was to investigate histologic changes in the rabbit meniscus after meniscal repair via radiofrequency energy (RFE)., Methods: Twenty Japanese white rabbits underwent bilateral knee arthrotomies, and a longitudinal tear was made in the avascular area of both medial menisci. On the right knees, RFE treatment (60 degrees C and 40 W) was performed on the femoral surface of the meniscal tear in monopolar mode. On the left knees, the meniscus was left untreated as a control. The rabbits were killed at 0, 1, 2, 4, or 12 weeks after surgery, and all medial menisci were examined histologically. The expression of autocrine motility factor in meniscal fibrochondrocytes was examined by immunohistochemical analysis., Results: Histologic examination at baseline showed fusion of collagen fibers in the tear. Failure of fusion was found in 2 of 4 menisci at 2 weeks and 1 of 4 menisci at 4 and 12 weeks. One week after surgery, the specimens showed an acellular area as a result of fibrochondrocyte death. The acellular area expanded deeper until 4 weeks and was reduced at 12 weeks. On the femoral surface of the RFE-treated area, fibroblast proliferation was found at 2 weeks, and fibroblasts had invaded into the meniscus tissue from the meniscal surface at 12 weeks. Immunohistochemical analysis showed that the expression of autocrine motility factor in RFE-treated menisci was significantly higher than that in control menisci from 1 to 12 weeks., Conclusions: RFE treatment at 60 degrees C and 40 W fused the collagen fiber in the meniscal tear in rabbits just after surgery. After RFE treatment, an acellular area developed as a result of fibrochondrocyte damage. RFE caused fibroblast proliferation at 2 weeks. The acellular area was reduced by cell repopulation at 12 weeks., Clinical Relevance: RFE may induce fibroblast proliferation for meniscal repair.

Orthopedic treatment with radiofrequency energy (RFE) was first used in shoulder surgery, and its effectiveness has been reported. The purpose of RFE treatment of soft tissue is to induce qualitative changes in collagen and obtain stability. Hypermobile lateral meniscus (HLM) is characterized by abnormal mobility resulting from rupture or defects of the popliteomeniscal fasciculi, but no satisfactory treatment has been reported. We followed up patients with HLM who underwent monopolar RFE treatment and confirmed its short-term effects by magnetic resonance imaging and second-look arthroscopy.