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Background: Distal femoral varus osteotomy (DFVO) is an established surgical procedure for addressing valgus malalignment across various knee conditions. However, the effect of DFVO on stress distribution within the femorotibial joint has not been explored through in vivo studies. Purpose: To (1) explore the distribution pattern of subchondral bone density across the proximal tibia in nonarthritic knees without arthritis and in those of patients with valgus knees, (2) assess changes in the pattern of bone density distribution in patients with valgus knees before and after medial closing-wedge (MCW) DFVO, and (3) determine the correlation between leg alignment and changes in bone density distribution. Study Design: Cohort study; Level of evidence, 3. Methods: The authors retrospectively analyzed clinical and radiographic data from 14 patients (14 knees; mean age, 44 years; 3 men, 11 women) treated with MCW-DFVO for lateral compartment osteoarthritis (OA) due to valgus malalignment, alongside a control group of 18 patients (18 knees; mean age, 21 years; 4 men, 14 women) without OA. The distribution patterns of subchondral bone density distribution on the femorotibial articular surface of the tibia were examined both preoperatively and >1 year postoperatively using computed tomography osteoabsorptiometry. Quantitative analyses were conducted on the locations and percentages of the high-density areas (HDAs) on the articular surface. The mean time between surgery and the postoperative radiograph and computed tomography absorptiometry imaging was 13.6 months (range, 11-19 months). The mean length of clinical follow-up was 28.7 months (range, 14-62 months) after surgery. Results: The mean proportion of HDA in the lateral compartment relative to the total HDA (lateral ratio) was significantly greater in the preoperative OA group (58.8%) compared with the control group (41.1%) (P <.001). After MCW-DFVO, the mean lateral ratio in the OA group notably declined to 45.3% (P <.001). The lateral ratio exhibited a significant correlation with the hip-knee-ankle angle in both the control (r = 0.630; P =.011) and OA (r = 0.537; P =.047) groups. Moreover, the alteration in the lateral ratio after MCW-DFVO showed a significant relationship with changes in the hip-knee-ankle angle (r = 0.742; P =.002) and the mechanical lateral distal femoral angle (r = −0.752; P =.002). Within the lateral compartment, HDAs in the 3 lateral regions of the 4 lateral subregions diminished after MCW-DFVO, whereas in the medial compartment, HDAs in the 3 lateral subregions saw an increase. Conclusion: The mean lateral ratio was significantly greater in the preoperative OA group compared with the control group. MCW-DFVO resulted in a redistribution of HDA from the lateral to the medial compartment of the proximal tibial articular surface. The extent of alignment correction after MCW-DFVO was closely linked to the shifts in HDA distribution, reflecting changes in stress distribution. [ABSTRACT FROM AUTHOR]

Background: Recent studies have reported that medial opening wedge (OW) high tibial osteotomy (HTO) induces patella baja, resulting in degenerative changes in the patellofemoral joint. We have developed an inverted V-shaped (iV) HTO, which is classified as a neutral wedge osteotomy. Hypotheses: The study hypotheses were as follows: (1) patellar height, posterior tibial slope, and tibial length will not change between pre- and postoperative evaluations after iV-HTO; (2) the lateral shift ratio of the patella and the distance between the tibial tubercle and the trochlear groove may be significantly decreased after iV-HTO. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 191 patients (220 knees) who underwent HTO for medial osteoarthritis were enrolled retrospectively in this study: 107 knees underwent OW-HTO and 113 knees underwent iV-HTO. Clinical and radiological evaluations were performed before and at least 3 years after surgery. Results: Postoperatively, the mean Caton-Deschamps ratio was significantly decreased (P <.0001) from 0.95 to 0.79 in the OW group, while there were no significant changes in the iV group. The mean posterior tibial slope was significantly increased (P <.0001) from 8.5° to 10.5° in the OW group, while there were no significant differences in the iV group. Although the entire leg length was significantly increased (P <.0003) in both groups after HTO, there were no significant differences in tibial length between the pre- and postoperative periods in the iV group. Regarding the congruity of the patellofemoral joint, the mean lateral shift ratio did not significantly change in the OW group, whereas it was significantly decreased (P =.0012) from 11.5% to 8.8% in the iV group. The mean tibial tubercle–trochlear groove distance was significantly decreased (P <.0001) from 12.8 to 9.7 mm in the iV group, while it was significantly increased in the OW group (P <.0001). Concerning the clinical outcome, the Japanese Orthopaedic Association (JOA) and Lysholm knee scores at final follow-up (OW vs iV: JOA, 91.2 vs 90.1; Lysholm, 92.5 vs 89.0) were significantly increased (P <.0001) as compared with the preoperative values (OW vs iV: JOA, 68.3 vs 66.8; Lysholm, 67.9 vs 61.0). Conclusion: Patellar height, posterior tibial slope, and tibial length did not change after the iV-HTO, while they were significantly changed after the OW-HTO. Although the preoperative degrees of varus knee and patellofemoral osteoarthritis were more severe in the iV group than the OW group, the iV-HTO led to altered patellofemoral joint congruity. [ABSTRACT FROM AUTHOR]

Background: Remnant tissue preservation may be important in improving graft healing after anterior cruciate ligament (ACL) reconstruction, but it has yet to be established whether remnant tissue preservation improves the control of pivot-shift laxity. Hypothesis: The amount of ACL graft coverage with preserved remnant tissue improves the control of pivot-shift laxity, as qualitatively determined with an electromagnetic device. Study Design: Cohort study; Level of evidence, 3. Methods: The 3-dimensional kinematics were evaluated intraoperatively using an electromagnetic sensor system in 38 patients at the time of anatomic double-bundle ACL reconstruction with remnant tissue preservation and again at a minimum of 12 months postoperatively. The magnitude of the peak coupled anterior tibial translation (pCAT) and the maximal acceleration of posterior translation (APT) during the pivot-shift test were evaluated. The degree of graft coverage by remnant tissue was determined arthroscopically at the end of surgery, which was evaluated quantitatively using a scoring system (0-9 points). The relationship between the values during the pivot-shift test and preoperative and intraoperative factors were assessed. Results: The mean (±SD) side-to-side difference of the pCAT (ΔpCAT) was significantly (P < .0001) improved from 14.0 ± 5.0 mm to 2.6 ± 1.1 mm. Also, the mean side-to-side difference of the APT (ΔAPT) was significantly (P < .0001) improved from 525.6 ± 99.7 mm/s2 to 32.9 ± 23.6 mm/s2. The mean initial graft coverage score was 5.3 ± 2.6. The correlation analysis demonstrated that the degree of initial graft coverage was significantly correlated with the ΔpCAT (r = −0.517, P = .0007) and ΔAPT (r = −0.532, P = .0005). The status of the reconstructed graft at second-look arthroscopic surgery showed no significant correlations with the degree of initial graft coverage or the results of the pivot-shift test. Conclusion: The present study demonstrated that the preservation of ACL remnant tissue in anatomic double-bundle ACL reconstruction appears to improve the control of pivot-shift laxity at a minimum of 12 months postoperatively, as measured by an electromagnetic device. This improvement was significantly affected by the degree of intraoperative graft coverage with preserved remnant tissue. [ABSTRACT FROM AUTHOR]

Background: There is controversy regarding the efficacy of remnant tissue preservation on graft healing in anterior cruciate ligament (ACL) reconstruction. Hypothesis: The preserved remnant tissue will (1) adhere to the graft surface and undergo a remodeling process, (2) accelerate graft revascularization, (3) increase the number of graft mechanoreceptors by 4 weeks, and (4) improve anteroposterior knee laxity and structural properties of the graft by 12 weeks. Study Design: Controlled laboratory study. Methods: Forty-two sheep were randomly divided into 2 groups of 21 animals. In group I, the ACL was completely removed. In group II, the ACL was transected at the midsubstance but not debrided. ACL reconstruction was performed using a semitendinosus tendon autograft in both groups. Histological changes of the grafted tendon and the remnant tissue were evaluated at 4 and 12 weeks after surgery. Biomechanically, anterior translation and knee joint stiffness under an anterior drawer force and the structural properties of the femur-graft-tibia complex were evaluated. Results: The preserved remnant tissue was histologically distinct from the graft at 4 weeks, while the tissue partially adhered to the graft surface at 12 weeks. The ACL remnant tissue significantly accelerated revascularization in the grafted tendon at 4 weeks and significantly increased the number of mechanoreceptors at 4 and 12 weeks. In addition, remnant preservation significantly improved anterior translation (9.3 ± 2.1 mm and 5.4 ± 1.7 mm at 60° of knee flexion in groups I and II, respectively) and knee joint stiffness at 12 weeks. However, there were no significant differences in the structural properties between the 2 groups at 4 and 12 weeks after surgery. Conclusion: Preservation of the ACL remnant tissue in ACL reconstruction enhanced cell proliferation, revascularization, and regeneration of proprioceptive organs in the reconstructed ACL and reduced anterior translation. However, remnant preservation did not improve the structural properties of the graft. Clinical Relevance: These results imply that preservation of the ACL remnant tissue may improve graft healing after ACL reconstruction. [ABSTRACT FROM AUTHOR]

Anterior cruciate ligament reconstruction is a frequently performed orthopaedic procedure. Although short-term results are generally good, long-term outcomes are less favorable. Thus, there is renewed interest in improving surgical techniques. Recent studies of anterior cruciate ligament anatomy and function have characterized the 2-bundle structure of the native ligament. During non-weightbearing conditions, the anteromedial (AM) and posterolateral (PL) bundles display reciprocal tension patterns. However, during weightbearing, both the AM and PL bundles are maximally elongated at low flexion angles and shorten significantly with increasing knee flexion. Conventional single-bundle reconstruction techniques often result in nonanatomic tunnel placement, with a tibial PL to a femoral "high AM" tunnel position. In vitro studies have demonstrated that these nonanatomic single-bundle reconstructions cannot completely restore normal anterior-posterior or rotatory laxity. Cadaveric studies suggest that anatomic single-bundle and anatomic double-bundle reconstruction may better restore knee stability. Although many cadaver studies suggest that double-bundle reconstruction techniques result in superior stability when compared with single- bundle techniques, others failed to demonstrate a clear benefit of this more complex procedure. Cadaver studies generally do not apply physiologically relevant loads and provide only a "time-zero" assessment that ignores effects of healing and remodeling after anterior cruciate ligament reconstruction. In vivo, dynamic studies offer the most comprehensive assessment of knee function after injury or reconstruction, as they can evaluate dynamic stability during functional joint loading. Studies of knee kinematics during activities such as gait and running suggest that nonanatomic single-bundle anterior cruciate ligament reconstruction fails to restore preinjury knee function under functional loading conditions. Similar studies of more anatomic single- and double-bundle surgical approaches are in progress, and preliminary results suggest that these anatomic techniques may be more effective for restoring preinjury knee function. However, more extensive, well-designed studies of both kinematics and long-term outcomes are warranted to characterize the potential benefits of more anatomic reconstruction techniques for improving long-term outcomes after anterior cruciate ligament reconstruction. [ABSTRACT FROM AUTHOR]

Background: In the autogenous tendon for anterior cruciate ligament reconstruction, intrinsic fibroblasts are necrotized immediately after surgery, and repopulation and revascularization occur. Vascular endothelial growth factor is considered to be a potent mediator of angiogenesis. Hypothesis: An application of vascular endothelial growth factor significantly enhances angiogenesis in the in situ frozen anterior cruciate ligament, and the application significantly affects mechanical properties of the in situ frozen anterior cruciate ligament. Study Design: Controlled laboratory study. Methods: Right anterior cruciate ligaments from 66 rabbits underwent the freeze-thaw treatment, and animals were then divided into 3 groups. Group I served as a freeze-thaw but otherwise untreated control. In group II, 0.2 mL phosphate-buffered saline alone was applied. In group III, 30 μg vascular endothelial growth factor was applied. The groups were compared on the basis of histologic revascularization examinations using the Chalkley score, an indicator of the microvessel density, and mechanical evaluations, which included the anterior-posterior translation of the tibia relative to the femur during ±10 N of anterior-posterior load and the mechanical properties of the anteromedial bundle of the anterior cruciate ligament. Results: Group Ill's Chalkley score was significantly greater than that of groups I and II. The tensile strength and the tangent modulus of anterior cruciate ligaments in groups I, II, and Ill were significantly lower than those of a normal anterior cruciate ligament, although there were no significant differences among groups I, II, and Ill. Conclusion: Vascular endothelial growth factor, as administered in this study, significantly promoted angiogenesis in the devitalized anterior cruciate ligament with in situ freeze-thaw treatment, but it did not affect the mechanical properties of the in situ frozen-thawed anterior cruciate ligament in the rabbit model. Clinical Relevance: An application of the recombinant anterior cruciate ligament is a potential future strategy to enhance revascularization of the autograft in anterior cruciate ligament reconstruction. [ABSTRACT FROM AUTHOR]

Background: Biomechanical behaviors of posterior cruciate ligament reconstructions under cyclic loading have not been sufficiently clarified. Hypothesis: Biomechanical behaviors of the reconstruction that involves use of flexor tendons and an Endobutton are significantly different under cyclic loading from behaviors of the two standard reconstructions in which bone-patellar tendon-bone graft is used. Study Design: Controlled laboratory study. Methods: In a porcine model, the tendon/Endobutton reconstruction, the tendon-bone/interference screw reconstruction, and the tendon-bone/tibial-inlay reconstruction were biomechanically compared by using two cyclic tests. In each group of 15 specimens, 5 knees underwent tensile testing without cyclic loading, and the remaining 10 underwent the same tensile test after 5000 cycles of load-controlled or displacement-controlled loading. Results: At the 5000th cycle, the peak displacement or the peak load was affected by each type of cyclic loading to a significantly greater degree in the knees with the tendon/Endobutton procedure than in the knees reconstructed with the other two procedures. Conclusions: Plastic deformation occurred more easily during cyclic loading in the knees with the tendon/Endobutton reconstruction than in the knees with the tendon-bone reconstructions. Clinical Relevance: When the tendon/Endobutton reconstruction is used, a longer period of postoperative immobilization is necessary. [ABSTRACT FROM AUTHOR]

Determines the amount of load that should be applied during the anterior drawer test to detect the integrity of the anterior talofibular ligament. Schema of the experimental fixture used to apply loads to the cadaveric ankle; Measurement of anterior ankle laxity; Repeatability analysis of the in vivo measurement of ankle laxity without any ankle injuries.

Presents a study that compared the effects of initial graft tension on the biochemical behavior of the femur-graft-tibia complex during and after cyclic displacement. Influence of initial graft tension on the long-term results of anterior cruciate ligament (ACL) reconstruction; ACL reconstruction procedures used; Method of reconstruction for the femur-graft-tibia complexes; Changes in graft tension during cyclic displacement.

Presents information on a study which clarified biomechanically and histologically the effect of graft-tunnel diameter disparity on intraosseous healing of the flexor tendon graft within the bone tunnel in anterior cruciate ligament reconstruction. Materials and methodology of the study; Results of the study; Conclusion.

Reports a case of consecutive avulsion fractures involving the anterior cruciate ligament (ACL) in which a tibial attachment avulsion fracture was followed by a femoral attachment avulsion fracture. Use of an arthroscopic approach for repair of the initial avulsion of the ACL; Explanation for the residual instability even after anatomic reduction of the avulsion fractures; Description of the mechanism of the second avulsion fracture.

Presents information on a study which clarified the effect of nonphysiologically high initial tension on the mechanical and histologic properties of in situ frozen anterior cruciate ligaments. How the study was conducted; Results and discussion.

Provides information on a study which clarified the influence of cyclic displacement on the structural properties of four types of femur-graft-tibia complexes used to reconstruct the anterior cruciate ligament. Materials and methods; Results and discussion.

Presents a study examined the compensatory muscle activity in the posterior cruciate ligament-deficient knee during isokinetic knee motion. Materials and methods used in the study; Discussion of the results.

Clarifies the effects of initial graft tension on clinical outcome after arthroscopically assisted anterior cruciate ligament reconstruction. Materials and methodology of the study; Findings and analysis of results; Conclusions.

Examines whether the resumption of loading on autografts after augmentation procedures can recover the mechanical properties of the grafts deteriorated by complete stress shielding. Use of Japanese White rabbits in the experiment; Decreased tensile strength of the patellar tendon after complete stress shielding; Increased strength in the tendon after restressing.

Distinguishes between morbidity caused by harvesting semitendinosus and gracilis tendons and morbidity associated with anterior cruciate ligament (ACL) reconstruction surgery by studying patients who underwent ACL reconstruction using these tendons. Increase in the isometric and isokinetic strength of the quadriceps and hamstring muscles; Effects of tendon harvest on muscle strength.

Determines the effects of partial and complete stress shielding on mechanical properties and histology of in situ frozen patellar tendons of Japanese White rabbits. Comparison of reduction of tendon tension between groups; Comparison of tensile strengths; Comparison of patellar tendon cross-sectional areas; Histologic findings.

Determines the ability of prophylactic knee braces to reduce or limit medial collateral and anterior cruciate ligament elongation under dynamic loading conditions, by using cadaveric specimens that had a surrogate soft tissue material that matched the tissue compliance of in vivo contracted muscles. Materials and methods; Results; Discussion.

Presents a study stating the results of knee instability and muscle strength after anterior cruciate ligament reconstruction using an autologous graft harvested from the central one-third of the patellar and quadriceps tendon was performed in 65 knees of 65 patients who were followed from three to seven years. Materials and methods; Results; Discussion.

Biomechanical analysis of the two-dimensional models composed from roentgenographic pictures and electro myographic analysis of the shear force exerted on the tibia during standing on both legs were conducted in 21 young adult males. The simultaneous contraction of the quadriceps and hamstrings was observed in all electromyograms. Amplitude observed on electromy ograms of the hamstrings increased as the trunk flexion angle increased. The calculated average values of shear force were negative at every knee flexion angle (nega tive value means posteriorly directed force). As the trunk flexion angle increased, posterior drawer force increased at knee flexion angles of 30° and 60°. The simultaneous contraction of the quadriceps and the hamstrings was considered to be the main factor that influenced these results. Standing on both legs with knee and trunk flexion was considered to be applicable in the early stages after anterior cruciate ligament re construction. [ABSTRACT FROM PUBLISHER]

We measured the changes in distance between the tibial and femoral attachment points of the extraarticular ACL substitute during knee motion. To measure the changes in distance continuously and directly, a com puter-assisted experimental system was developed using an electrolyte-in-rubber transducer. We used 6 cadaveric knees to measure changes in distance of 15 combinations during a simple flexion and extension knee motion. The distance became longer with flexion in each pair of attachment locations. Although the small est change in distance was obtained between the pos terolateral site of the femoral distal metaphysis and a point posterior to the Gerdy tubercle (percent average of the maximum strain was about 12%), it was con cluded that the extraarticular ACL reconstruction is not recommended from a standpoint of isometry of the substitute. [ABSTRACT FROM PUBLISHER]