Less tunnel enlargement in triple-bundle versus double-bundle anterior cruciate ligament reconstruction: A randomized clinical trial.

BACKGROUND: No study thus far has compared tunnel enlargement between double-bundle and triple-bundle anterior cruciate ligament reconstruction. We compared tibial tunnel enlargement and rate of tibial tunnel coalition between these two reconstructions, hypothesizing that tibial tunnel enlargement in triple-bundle reconstruction is less than that in double-bundle reconstruction, and that the tunnel coalition rate is equal between the two procedures. METHODS: This prospective randomized clinical trial included 25 patients who underwent computed tomography 2 weeks and 1 year postoperatively. Eleven patients underwent double-bundle anterior cruciate ligament reconstruction and 14 underwent triple-bundle anterior cruciate ligament reconstruction. Tunnel positions and tunnel coalition at the tibial tunnel aperture were assessed using three-dimensional computed tomography. Tunnel enlargement rate was calculated by measuring the sagittal and axial widths of the tibial bone tunnel 10 mm from the tibial tunnel aperture. These parameters were then compared between the groups. RESULTS: The changes in tunnel positions and tunnel coalitions between groups were not significantly different. On both sagittal and axial views, the tunnel enlargement rates of the medial and lateral sections of the anteromedial bundle in the triple-bundle group were significantly smaller than those in the double-bundle group (sagittal view, p = 0.02 and < 0.01, respectively; axial view, p = 0.02 and ≤ 0.05, respectively). The groups did not differ significantly in terms of posterolateral tunnel enlargement. CONCLUSION: Tunnel widening in the medial and lateral sections of the anteromedial bundle-associated tibial tunnel in triple-bundle anterior cruciate ligament reconstruction was smaller than that of double-bundle reconstruction. The tunnel coalition rates between the two reconstructions were not significantly different.

The prevalence of posterior inferior tibiofibular ligament and inferior tibiofibular transverse ligament injuries in syndesmosis-injured ankles evaluated by oblique axial magnetic resonance imaging: a retrospective study.

BACKGROUND: Transverse ligament and posterior inferior tibiofibular ligament injuries have not been investigated till date because these are difficult to evaluate using standard magnetic resonance imaging. This study aimed to investigate the prevalence of transverse ligament and posterior inferior tibiofibular ligament injuries in syndesmosis-injured ankles using oblique axial magnetic resonance imaging. METHODS: The patients who were diagnosed with syndesmosis injury using magnetic resonance imaging (MRI) within 7 days of the trauma were included. Patients with concomitant fractures were excluded. A total of 34 patients (1 woman and 33 men) with an average age of 22 years (range, 14-64 years) were included. The anterior inferior tibiofibular, interosseous, transverse, and posterior inferior tibiofibular ligaments were classified as intact, partial tear, or complete tear using usual axial and oblique axial MRIs. RESULTS: There were 8 (23.5%) ankles with an intact, 21 (61.8%) ankles with a partially torn, and 5 (14.7%) ankles with a complete tear of transverse ligament. There were 20 (58.8%) ankles with an intact, 12 (35.3%) ankles with a partially torn, and 2 (5.9%) ankles with a complete tear of posterior inferior tibiofibular ligament. Overall, 50% of the transverse ligament injuries occurred without posterior inferior tibiofibular ligament involvement. CONCLUSIONS: The oblique axial magnetic resonance imaging scan revealed that the prevalence of transverse ligament and posterior inferior tibiofibular ligament injuries in syndesmosis-injured ankles were 76.5 and 41.2%, respectively.

Functional Adaptation of the Fibrocartilage and Bony Trabeculae at the Attachment Sites of the Anterior Cruciate Ligament.

The direct insertion of an enthesis is composed of uncalcified fibrocartilage (FC) and calcified FC, believed to function as buffers for multidirectional forces applied to the ligament. This study was performed to investigate the relationship between the FC thickness and bony trabecular orientation of the anterior cruciate ligament (ACL) on both the femoral and tibial sides. Six cadavers were examined (age at death: 73-92 years). Both femoral and tibial insertions of the ACL were harvested and used to make 0.5 mm interval semi-serial sections. Microdigital images were taken and used to measure the maximum thickness of both the uncalcified FC and Calcified FC. Two-dimensional discrete Fourier analysis was also performed to determine the orientation angle and orientation intensity of bony trabeculae directly under the FC. The mean thicknesses of the uncalcified FC at the femoral and tibial insertions were 0.98 mm and 0.49 mm, respectively. The mean thicknesses of the calcified FC were 0.47 mm and 0.38 mm, respectively. There was a significant difference in the uncalcified FC thickness, but not in the calcified FC thickness. The bony trabeculae showed a prominent orientation parallel to the ACL fiber on both sides, but it was more intense on the tibial side than on the femoral side. The trabecular orientation was prominent in the proximal-posterior part of the femoral side and in the anteromedial part of the tibial side, suggesting that mechanical stress is greater in these parts. The dominant bony trabecular angle was 69.0° on the femoral side and 59.8° on the tibial side when the tidemark was set at 0°. These findings suggest that the femoral side receives multidirectional stresses, while relatively unidirectional stress is loaded on the tibial side. Furthermore, stress is considered to be greater in the proximal-posterior part of the femoral insertion and in the anteromedial part of the tibial insertion. At the time of ACL reconstruction, attention should be paid to assign a robust portion of the graft to the posterior part of the femoral insertion and anteromedial part of the tibial insertion. Clin. Anat., 33:988-996, 2020. © 2019 Wiley Periodicals, Inc.

A Biomechanical Comparison of Single-, Double-, and Triple-Bundle Anterior Cruciate Ligament Reconstructions Using a Hamstring Tendon Graft.

PURPOSE: The first objective of our cadaveric study was to perform a biomechanical comparison of single-bundle (SB), double-bundle (DB), and triple-bundle (TB) anterior cruciate ligament (ACL) reconstructions using a hamstring tendon graft to determine the laxity match pre-tension (LMP) value, which is the tension within the graft required to re-create the same anterior laxity as the ACL-intact knee. The second objective was to determine the anterior laxity and force distribution during the application of both an anterior force and a simulated pivot-shift test. METHODS: Eleven fresh-frozen cadaveric knees were tested using a robotic/universal force-moment sensor system in the intact state, TB-reconstructed knee, DB-reconstructed knee, and SB-reconstructed knee. The LMP in each reconstruction was recorded. Each reconstructed knee was tested with an external load of 100-N anterior drawer and combined rotatory loads of 10-Nm valgus moment and 5-Nm internal rotation. The anterior tibial translation and tensile forces of each graft bundle were measured. RESULTS: The LMP values for the TB reconstruction were 1.7 N for the anteromedial-medial graft, 1.7 N for the anteromedial-lateral graft, and 3.4 N for the posterolateral graft (PLG). The LMP value was 5.6 N for the anteromedial graft and PLG in the DB reconstruction. The LMP value was 26.3 N for the whole graft in the SB reconstruction. No statistically significant difference in stability was found between TB and DB reconstructions during the anterior load and the combined rotatory load test. For force distribution, the PLG tension in the TB reconstruction was statistically lower than that in the DB reconstruction. CONCLUSIONS: Anatomic TB ACL reconstruction with the lowest initial tension on the graft stabilized the knee equally to DB or SB reconstruction, which required greater initial tension. CLINICAL RELEVANCE: Although SB, DB, and TB ACL reconstructions through the anatomic tunnel position could equally restore stability, the initial tension on the graft required to restore stability was less in the latter 2 multi-tunnel reconstructions.

Midterm outcomes after arthroscopic surgery for hypermobile lateral meniscus in adults: Restriction of paradoxical motion.

BACKGROUND: Hypermobile lateral meniscus (HLM) is one of the causes of knee pain and a locking sensation. It is thought that disruption of the popliteomeniscle fascicles lead to hypermobility of the lateral meniscus in adults. In cases of HLM, the posterior portion of the lateral meniscus shows forward abnormal translation with knee flexion and backward translation with knee extension. We refer to this phenomenon as paradoxical motion. The purpose of this study was to report an arthroscopic HLM stabilization and evaluate the midterm clinical outcomes. METHODS: Twenty consecutive HLM patients (21 knees) who underwent arthroscopic surgery were included. The mean age at the time of surgery was 37.7 (19-63) years. Mean duration from surgery to final follow-up was 37 (24-68) months. Meniscus movement according to the knee flexion and extension was observed by diagnostic arthroscopy. We performed arthroscopic inside-out vertical stacked suturing of disrupted popliteomeniscle fascicles. The number of suturing and details of meniscal movement were assessed. The Tegner activity level score and Lysholm knee scores were determined preoperatively and at 2 years postoperatively. Clinical outcomes included locking sensation, recurrences and complications reported at the final follow-up. RESULTS: Paradoxical motion of the lateral meniscus was observed in all patients. We performed an average of 5.0 (2-8) vertical stacked sutures of the disrupted popliteomeniscal fascicles. Physiological motion of the lateral meniscus was observed after meniscus repairs. The mean Tegner activity level scales before and after surgery were 4.6 (2-8) and 4.7 (2-8), respectively. The mean Lysholm knee scores significantly improved from 72.0 (48-85) preoperatively to 97.8 (78-100) at 2 years postoperatively. There were no complications or recurrences of locking symptoms at the final follow-up. CONCLUSIONS: Use of arthroscopic inside-out vertical sutures for disrupted popliteomeniscle fascicles improved the clinical outcomes for HLM patients without complications.

Ultrastructure of the three anterior cruciate ligament bundles.

The anterior cruciate ligament (ACL) can be morphologically separated into not only two, but three bundles: the anteromedial-medial bundle (AM-MB), the anteromedial-lateral bundle (AM-LB), and the posterolateral bundle (PLB). Our hypothesis was that the three bundles differ in their microstructures. The purpose of this study was to clarify the microstructural differences among the three bundles. The normal ACLs of six fresh frozen cadavers were harvested. After the AM-MB, AM-LB, and PLB were identified, their fibril structures were analyzed using a transmission electron microscope. The fibril orientation, distribution pattern, and the mass average diameter of the fibrils (MAD) were compared among the AM-MBs, AM-LBs, and PLBs. The AM-MB and AM-LB fibrils were arranged mostly in the longitudinal direction, while the PLB fibrils were not aligned in a uniform direction. The fibril diameter distribution pattern of AM-MBs showed a bi-modal pattern due to the existence of small-diameter (30-40 nm) and large-diameter fibrils (70-80 nm), while that of the AM-LBs and PLBs had a unimodal pattern with one prominent high peak at a diameter of 50-60 nm. The mean MAD of the AM-MBs (83.2 - 11.2 nm) was significantly larger than that of the PLBs (66.8 - 7.7 nm), while it showed no significant difference compared to that of the AM-LBs (77.6 - 12.3 nm). The three ACL bundles have different ultrastructures. The AM-MB predominantly includes thick, uni-directionally oriented fibrils like tendons, while the PLB consists of thinner, multi-directionally oriented fibrils. The AM-LB shows an intermediate structure between the AM-MB and the PLB.

Biomechanical comparison between the rectangular-tunnel and the round-tunnel anterior cruciate ligament reconstruction procedures with a bone-patellar tendon-bone graft.

PURPOSE: The purpose of this study was to evaluate the effectiveness of 2 anterior cruciate ligament (ACL) reconstruction techniques using a bone-patellar tendon-bone (BPTB) graft with femoral tunnel, either a rectangular tunnel (RET) or a round tunnel (ROT). METHODS: For experiment 1, nine fresh-frozen human cadaveric knees were tested with a robotic/universal force-moment sensor system to determine the initial optimal tension: the amount of graft tension at 15° of flexion most closely resembling the anterior laxity of a normal knee. The value was estimated by repeatedly measuring anterior laxity when 100 N of anteroposterior drawer load was applied to the knees at 30° of flexion after RET ACL or ROT ACL reconstruction. For experiment 2, six fresh-frozen human cadaveric knees were selected. On the basis of the initial tension determined in experiment 1, RET ACL reconstruction was conducted with the graft tensioned to 10 N, followed by ROT ACL reconstruction on the same knee at 40 N of initial tension, and the biomechanical efficacy of the 2 methods was compared. RESULTS: For experiment 1, the mean laxity match tension at 15° of flexion was 8.6 ± 4.8 N and 34.8 ± 9.2 N for RET- and ROT-reconstructed knees, respectively. For experiment 2, both RET and ROT ACL reconstructions were successful in controlling anterior tibial translation under anterior tibial loads, with the graft initially tensioned to 10 N in the former and to 40 N in the latter. However, the greater tensioning in ROT reconstruction led to proximal, posterior, and lateral displacement of the tibia along with its external and valgus rotation. CONCLUSIONS: The RET ACL-reconstructed knee more closely resembled the normal knee in biomechanical behavior. Although ROT reconstruction successfully controlled anterior translation with greater initial tensioning to the graft, the normal positional relation between the tibia and femur was impaired. CLINICAL RELEVANCE: Rectangular femoral ACL fixation constructs and grafts may prove more efficacious at restoring in vivo ACL kinematics than round femoral tunnels.

Outcomes of knee arthrodesis following infected total knee arthroplasty: a retrospective analysis of 8 cases.

BACKGROUND: There is insufficient information regarding patient-based outcomes after knee arthrodesis following infected total knee arthroplasty (TKA). The purpose of this study was to analyze outcomes in patients who underwent knee arthrodesis following infected TKA using clinical and radiographic measurements including a patient-based outcome measuring system. METHODS: We evaluated 8 patients (mean age 72.9 years) who were followed for more than 3 years after arthrodesis. Clinical and radiographic evaluation was performed, including examination of the patient's function and use of supportive equipment for walking. The Japanese knee osteoarthritis measurement (JKOM) was used for measuring patient-based outcomes and health-related quality of life. RESULT: Knee fusion was achieved in 7 patients. The mean limb-length discrepancy was 5.4 cm. All patients could walk at least inside the house, and activity of daily living (ADL) independence was achieved by the patients with successful knee fusion, although walking aids, including a shoe lift causing little discomfort, were required. The results of JKOM for the patients with successful fusion were comparable to the data for patients who underwent TKA. CONCLUSIONS: When knee arthrodesis was performed for infected TKA cases, pain was reduced and ADL independence was established when knee fusion was achieved. This study demonstrated that information from subjective and functional evaluations of knee arthrodesis patients is useful in understanding postoperative activity and situations, and revealed the importance of supportive elements for walking.

Factors affecting the post-operative over-constraint after anatomic double-bundle anterior cruciate ligament reconstruction.

Objective: Initial tension at graft fixation is one of key factors for good outcomes in anterior cruciate ligament (ACL) reconstruction. Identifying the pre-operative factors that influence postoperative knee laxity under the anterior tibial load is useful in determining the initial tension at graft fixation. Thus, the purpose of this study was to clarify the pre-operative factors affecting the side-to-side difference in anterior laxity immediately after the anatomic double-bundle ACL reconstruction with a constant initial tension. Methods: Fifty-five patients underwent the anatomic double-bundle ACL reconstruction with hamstring tendon grafts. Anterior tibial displacement (ATD) was measured on both knees using KT-2000 Knee Arthrometer under anterior drawer load of 67 N, 89 N, 134 N and manual maximum load at 30° of flexion before ACL reconstruction under anesthesia, and was also measured on the operated knees under 89 N immediately after ACL reconstruction under anesthesia. Then, side-to-side difference (SSD) before and immediately after ACL reconstruction was calculated. Correlative relation between the SSD immediately after ACL reconstruction and the ATD/the SSD in each condition was analyzed. Results: The side-to-side difference of ATD immediately after surgery was -3.8 ± 1.7 mm (0 to -8mm) in response of 89 N of anterior load. There was correlation between the SSD immediately after ACL reconstruction and all ATD on both knees except for the ATD under manual maximum load on the injured knee, while little correlation between the SSD immediately after ACL reconstruction and that before ACL reconstruction was found. Especially, ATD under 89 N on the opposite knees and ATD under 134 N on the injured knees showed selective correlation with the SSD immediately after surgery in the step-wise multiple regression analysis. Conclusion: As the anterior tibial displacements under 89 N on the contra-lateral knee and under 134 N on the injured knee had a significant correlation with the SSD immediately after ACL reconstruction, those values may be helpful in determining the increase or decrease in initial tension at graft fixation.

Analysis of effectiveness of therapeutic exercise for knee osteoarthritis and possible factors affecting outcome.

BACKGROUND: There are numerous reports and evidences to suggest that exercise therapy is effective for knee osteoarthritis (knee OA). However, there is a lack of sufficient research concerning the factors influencing its application and effectiveness. The purposes of this study were to evaluate effects of the mode of treatment delivery on the improvement of symptoms in knee OA, and to analyze potential risk factors affecting improvement after exercise therapies. METHODS: The 209 women applicants diagnosed with knee OA were randomly allocated into either a group performing group exercise in a class or a group performing home exercise. The 90 min exercise program was performed under the guidance of physiotherapists as a group exercise therapy. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) of the subjects of both groups before and after intervention was compared to examine the effect of exercise therapy. In addition, body mass index, knee range of motion (ROM), the femorotibial angle from radiographs, OA severity from Kellgren-Lawrence grade, and meniscus abnormality and subchondral bone marrow lesions from MRI findings were statistically analyzed as factors that may affect exercise therapy. RESULTS: A significantly greater improvement in WOMAC was observed in the subjects of group exercise (81 subjects) as compared with the subjects of home exercise (122 subjects). There was a significantly high proportion of subjects with knee flexion contracture among the subjects participating in group exercise that showed only minor symptom improvement (p < 0.05). In addition, exercise therapy proved to be highly effective for subjects with limited quadriceps muscle strength (p < 0.05). CONCLUSIONS: When prescribing exercise therapy for knee OA, evaluation of a subject's ROM and muscle strength is important in deciding whether to commence exercise therapy and what type of exercise therapy to apply; it is also important in predicting the effect of exercise therapy.

Outcomes of knee arthrodesis following infected total knee arthroplasty: a retrospective analysis of 8 cases.

BACKGROUND: There is insufficient information regarding patient-based outcomes after knee arthrodesis following infected total knee arthroplasty (TKA). The purpose of this study was to analyze outcomes in patients who underwent knee arthrodesis following infected TKA using clinical and radiographic measurements including a patient-based outcome measuring system. METHODS: We evaluated 8 patients (mean age 72.9 years) who were followed for more than 3 years after arthrodesis. Clinical and radiographic evaluation was performed, including examination of the patient's function and use of supportive equipment for walking. The Japanese knee osteoarthritis measurement (JKOM) was used for measuring patient-based outcomes and health-related quality of life. RESULT: Knee fusion was achieved in 7 patients. The mean limb-length discrepancy was 5.4 cm. All patients could walk at least inside the house, and activity of daily living (ADL) independence was achieved by the patients with successful knee fusion, although walking aids, including a shoe lift causing little discomfort, were required. The results of JKOM for the patients with successful fusion were comparable to the data for patients who underwent TKA. CONCLUSIONS: When knee arthrodesis was performed for infected TKA cases, pain was reduced and ADL independence was established when knee fusion was achieved. This study demonstrated that information from subjective and functional evaluations of knee arthrodesis patients is useful in understanding postoperative activity and situations, and revealed the importance of supportive elements for walking.

Risk factors of lower extremity injuries in youth athletes.

Objective: Lower extremity sports injuries frequently occur during an individual's growth period. The object of the current study was to analyse the risk factors for lower extremity sports injuries for youth athletes. The secondary objective was to clarify the factors related to new injuries after a lower extremity injury. Methods: We extracted information on youth athletes (aged 10-15 years) with sports-related disorders. Background data and injury situations were collected via a specific application. During the follow-up period, new injuries were also recorded. The athletes were divided into two groups according to injury location (lower extremity or other). We performed a multiple logistic regression analysis to clarify the association between injury location and background data. Results: 1575 complaints of lower extremity disorders and 328 complaints in other body parts were registered. According to the multiple regression analysis, practice time per week was significantly shorter for the lower extremity group than the other locations group (OR 0.98; 95% CI 0.963 to 0.999). Athletes whose future goal was at the recreational level had a significantly low incidence of new injuries after experiencing lower extremity disorders. Conclusion: The practice environments and psychological factors should receive more attention to prevent lower extremity injuries.

The arrangement and the attachment areas of three ACL bundles.

PURPOSE: Normal anterior cruciate ligament (ACL) can be divided into three fiber bundles-i.e., anteromedial (AM), intermediate (IM), and posterolateral (PL) bundles. However, their arrangement and attachment areas had remained unclear. The purpose of this study was to clarify the arrangement of these three ACL fiber bundles and their attachment sites, and to provide information on the tunnel placement in anatomical triple bundle ACL reconstruction. METHODS: Seven non-embalmed human frozen knees were used. ACL fibers were bluntly divided into three bundles. A different-colored thread was wound around each fiber bundle in a spiral. Macroscopical investigation was performed to clarify the arrangement of three ACL bundles. Each fiber bundle was carefully detached from the femur and tibia, and then the distribution of attachment sites of each fiber bundle was observed. RESULTS: In knee extension, all bundles consisting of AM, IM and PL bundles ran parallel to each other in the lateral view from the medial side. The AM bundle overlapped with the IM bundle, whereas the PL bundle ran parallel to them on the distal aspects. As the knee flexion increased, the bundles became twisted around each other. On the tibial side, the attachment areas of three fiber bundles formed a triangular shape showing arrangements of AM, IM and PL bundles on the anteromedial, anterolateral and posterior aspects, respectively. On the femoral side, the PL bundle was attached on the distal-posterior areas; the IM bundle was attached distal-anterior to the AM bundle. They were arranged in a triangular shape on the tibia side as well. CONCLUSION: This study clarified the arrangement of three fiber bundles of ACL and detailed geographical locations of their attachment sites. The detailed anatomic description of the natural ACL attachment might suggest to surgeons where to make tunnels during anatomical double/triple bundle ACL reconstruction.

Triple-bundle ACL grafts evaluated by second-look arthroscopy.

PURPOSE: The purpose of this study was to evaluate the morphology of transplanted triple-bundle anterior cruciate ligament (ACL) grafts by second-look arthroscopy. METHODS: The subjects were 41 patients with a mean age of 25.5 ± 8.5 years who underwent second-look arthroscopy at between 6 and 22 months after the anatomical triple-bundle ACL reconstruction using semitendinosus tendon autograft. Lachman test was negative in 38 knees and mildly positive with a firm endpoint in 3 knees. Arthroscopic evaluation of grafts was performed for the anteromedial graft (AM), the intermediate graft (IM), and the posterolateral graft (PL), focusing on tension and graft damage. RESULTS: All grafts showed "fan-out" shape approaching the tibial attachment, which looked closer to the natural ACL compared to the double-bundle grafts. As to graft tension, 93% of AM, 90% of IM, and 88% of PL grafts were evaluated as taut, respectively. As to graft damage, there was no apparent rupture in the AM and IM grafts, while complete or substantial rupture was observed in 10% of PL grafts around the femoral tunnel aperture. The incidence of graft rupture in PL grafts was significantly greater than those in the AM and IM grafts. As to synovial coverage, 76% of AM, 78% of IM, and 59% of PL grafts were evaluated as "Good," while 41% of PL grafts were not fully covered with synovium. All of the synovial defects were observed around the femoral tunnel aperture. CONCLUSION: The morphology of the triple-bundle grafts resembled that of the natural ACL, while complete or substantial rupture was observed in 10% of the PL grafts. LEVEL OF EVIDENCE: Study of case series with no comparison group, Level IV.

Effect of Anterior Horn Tears of the Lateral Meniscus on Knee Stability.

Background: Investigations on the biomechanical characteristics of the anterior horn of the lateral meniscus (AHLM) related to anterior cruciate ligament (ACL) tibial tunnel reaming have revealed increased contact pressure between the femur and tibia, decreased attachment area, and decreased ultimate failure strength. Purpose/Hypothesis: The purpose of this study was to investigate the influence of a complete radial tear of the AHLM on force distribution in response to applied anterior and posterior drawer forces and internal and external rotation torques. We hypothesized that the AHLM plays an important role in knee stability, primarily at lower knee flexion angles. Study Design: Controlled laboratory study. Methods: A total of 9 fresh-frozen cadaveric knee specimens and a robotic testing system were used. Anterior and posterior drawer forces up to 89 N and internal and external rotation torques up to 4 N·m were applied at 0°, 30°, 60°, and 90° of knee flexion. A complete AHLM tear was then made 10 mm from the lateral border of the tibial attachment of the ACL, and the same tests performed in the intact state were repeated. Next, the recorded intact knee motion was reproduced in the AHLM-torn knee, and the change in the resultant force after an AHLM tear was determined by calculating the difference between the 2 states. Results: In the torn AHLM, the reduction in the resultant force at 0° for external rotation torque (34.8 N) was larger than that at 60° (5.2 N; P < .01) and 90° (6.7 N; P < .01). Conclusion: The AHLM played a role in facilitating knee stability against an applied posterior drawer force of 89 N and external rotation torque of 4 N·m, especially at lower knee flexion angles. Clinical Relevance: This study provides information about the effects of AHLM injuries that may occur during single-bundle ACL reconstruction using a round tunnel.

A Biomechanical Comparison of 2 Over-the-Top Anterior Cruciate Ligament Reconstruction Techniques: A Cadaveric Study Using a Robotic Simulator.

Background: For skeletally immature patients, over-the-top (OTT) anterior cruciate ligament (ACL) reconstruction (ACLR) is preferred. However, increased anterior laxity at deep knee flexion angles remains concerning. We modified the procedure to proximally shift the graft fixation site on the femur to prevent graft loosening at higher knee flexion angles and named it the supra-OTT procedure. Purpose: To compare anterior laxity and in situ forces of the ACL graft between conventional OTT and supra-OTT ACLR in a cadaveric model. Study Design: Controlled laboratory study. Methods: A total of 11 fresh-frozen cadaveric knee specimens underwent 4 robotic testing conditions: ACL intact, ACL resected, conventional OTT, and supra-OTT. For each condition, a 100-N load was applied at 0°, 15°, 30°, 60°, and 90° of knee flexion to simulate the Lachman test or anterior drawer test. In addition, a combined load of 5-N·m internal tibial torque and 10-N·m valgus torque was applied at 15° and 30° of knee flexion as a simulated pivot-shift test. Anterior tibial translation and in situ graft forces were recorded. The only difference between conventional OTT and supra-OTT ACLR was the graft fixation site on the femur. For conventional OTT ACLR, graft fixation was performed just on the proximal and lateral ends of the posterior condyle. For supra-OTT ACLR, the fixation point was around the proximal insertion of the lateral head of the gastrocnemius and the lateral edge of the posterior cortex, approximately 2 cm proximal to the conventional OTT position. Results: On the simulated anterior drawer test at 60° and 90° of knee flexion, anterior tibial translation after supra-OTT ACLR was significantly smaller than after conventional OTT ACLR (P < .01). However, no significant differences were noted at other flexion angles or on the simulated pivot-shift test between the conventional OTT and supra-OTT procedures. Some overconstraint and higher graft forces were noted with both techniques, but the supra-OTT technique caused even more overconstraint at higher flexion angles. Conclusion: Supra-OTT ACLR showed better biomechanical performance to control anterior laxity than conventional OTT ACLR at higher knee flexion angles. Clinical Relevance: The supra-OTT procedure may improve anterior stability at deep knee flexion angles.

The Role of the Medial Meniscus in Anterior Knee Stability.

Background: Few studies have compared the force distribution between the anterolateral, posterolateral, and medial structures of the knee. Purpose: To investigate the important structures in an intact knee contributing to force distribution in response to anterior tibial load. Study Design: Controlled laboratory study. Methods: Nine fresh-frozen cadaveric knee specimens underwent robotic testing. First, 100 N of anterior tibial load was applied to the intact knee at 0°, 15°, 30°, 60°, and 90° of knee flexion. The anterior cruciate ligament (ACL), anterolateral capsule, lateral collateral ligament, popliteal tendon, posterior root of the lateral meniscus, superficial medial collateral ligament, posterior root of the medial meniscus (MM), and posterior cruciate ligament were then completely transected in sequential order. After each transection, the authors reproduced the intact knee motion when a 100-N anterior tibial load was applied. By applying the principle of superposition, the resultant force of each structure was determined based on the 6 degrees of freedom force/torque data of each state. Results: At every measured knee flexion angle, the resultant force of the ACL was the largest of the tested structures. At knee flexion angles of 60° and 90°, the resultant force of the MM was larger than that of all other structures with the exception of the ACL. Conclusion: The MM was identified as playing an important role in response to anterior tibial load at 60° and 90° of flexion. Clinical Relevance: In clinical settings, the ACL of patients with a poorly functioning MM, such as tear of the MM posterior root, should be monitored considering the large resultant force in response to an anterior tibial load.

Early integration of a bone plug in the femoral tunnel in rectangular tunnel ACL reconstruction with a bone-patellar tendon-bone graft: a prospective computed tomography analysis.

PURPOSE: The purpose of this prospective study was to evaluate how early the bone plug was integrated into the rectangular femoral tunnel after anatomical ACL reconstruction using a bone-patellar tendon-bone (BTB) graft via a rectangular tunnel (RT BTB ACL-R). METHODS: Twenty consecutive patients who had undergone the reconstruction procedure were evaluated by CT scans at 4 and 8 weeks postoperatively. In each scan, 30 slices for multiplanar reconstruction were collected parallel to the long axis of the parallelepiped femoral tunnel and perpendicular to the tendinous plane of the bone plug. Each slice was classified as "complete," indicating no visible gap between the plug and the tunnel wall or trabecular continuity or "incomplete," showing a visible gap. Bone plug-tunnel integration was evaluated as "excellent," "good," "fair," or "poor" for >20, 11-20, 5-10, and <4 "complete" slices, respectively. RESULTS: In this evaluation, 55% of the patients were rated as "excellent" on the first scan, and 80% were "excellent" on the second scan, showing healing over time. The CT values at the anterior interface between the bone plug and the tunnel wall were also measured on both scans. The mean changes in CT value at 8 weeks were significantly lower than those at 4 weeks. CONCLUSION: This study shows that bone plug-femoral tunnel integration was almost complete by 8 weeks after surgery using RT BTB ACL-R.

Meniscus Repair With Anterior Cord Release for Peripheral Tear Type of Discoid Lateral Meniscus.

With improvement in arthroscopic techniques, partial meniscectomy with repair for symptomatic discoid lateral meniscus (DLM) has been the preferred treatment to restore meniscal function. It was reported that DLM exhibited deformation and extrusion shortly after saucerization with repair. Therefore it is desirable to minimize removal of the DLM. The anterior zone of the DLM is often tighter than that of the normal meniscus and anatomic variant. It is considered that the anterior and anterocentral dislocation types in the majority of symptomatic DLM can be related to both peripheral instability and anterior tightness. We present a technique that, first, the inside-out repair technique is applied from the posterior to middle segment of the DLM; next, the tension of the anterior zone during knee flexion-extension is confirmed to determine the released amount of that part; and, finally, all sutures are tied to reproduce the normal meniscus movement. Meniscus repair with anterior cord release without any meniscectomy could resolve peripheral instability of DLM and prevent degeneration of the articular cartilage.

Hamstring Graft Prepared With Suture Tape Is Effective in Anterior Cruciate Ligament Reconstruction: A Biomechanical Analysis.

PURPOSE: To investigate the graft diameters and mechanical properties of hamstring tendons sutured using different materials and techniques. METHODS: This study used 30 fresh, frozen human cadaveric semitendinosus tendons; the free ends of 10 specimens each were sutured by 2 No. 3 braided polyester sutures with the Krackow technique (BP group), SutureTape with the Krackow technique (ST group), or SutureTape Loop with the locking SpeedWhip technique (SL group). First, the changes in graft diameter from before suturing to after suturing were investigated. Each graft was pre-tensioned to 100 N for 3 cycles and then cyclically loaded to 200 N for 200 cycles. Elongation after cyclic loading and displacement in the 200th cycle were calculated. Finally, each specimen was loaded to failure. The ultimate failure load and stiffness were analyzed. These mechanical properties were statistically analyzed using 1-way analysis of variance. The level of statistical significance was set at P < .05. RESULTS: In the BP group, the changes in graft diameter were significantly larger than those in the ST and SL groups (P = .001). The elongation values after 200 cycles in the BP and ST groups were 3.1 ± 2.0 mm and 5.9 ± 3.4 mm, respectively. In the SL group, elongation (7.7 ± 3.6 mm) was significantly larger compared with that in the BP group (P = .037). In contrast, displacement in the 200th cycle was significantly smaller in the ST and SL groups compared with the BP group (P = .017). No statistically significant difference was evident for the ultimate failure loads among the 3 groups (P = .543). CONCLUSIONS: The results of this study suggest that SutureTape may be an appropriate option for preparing the hamstring graft in anatomic anterior cruciate ligament (ACL) reconstruction. CLINICAL RELEVANCE: This biomechanical study shows the effectiveness of SutureTape in ACL graft preparation. Clinically, SutureTape may be of benefit in single- or double-bundle ACL reconstruction.