Comparison of volumetric bone mineral density in the tibial region of interest for ACL reconstruction

Adequate tibial bone mineral density (BMD) is essential to soft tissue graft fixation during anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to compare volumetric bone plug density measurements at the tibial region of interest for ACL reconstruction using a standardized immersion technique and Archimedes’ principle. Cancellous bone cores were harvested from the proximal, middle, and distal metaphyseal regions of the lateral tibia and from the standard tibial tunnel location used for ACL reconstruction of 18 cadaveric specimens. Proximal tibial cores displayed 32.6% greater BMD than middle tibial cores and 31.8% greater BMD than distal tibial cores, but did not differ from the BMD of the tibial tunnel cores. Correlational analysis confirmed that the cancellous BMD in the tibial tunnel related to the cancellous BMD of the proximal and distal lateral tibial metaphysis. In conjunction with its adjacent cortical bone, the cancellous BMD of the region used for standard tibial tunnel placement provides an effective foundation for ACL graft fixation. In tibia with poor BMD, bicortical fixation that incorporates cortical bone from the distal tibial tunnel region is recommended.     

Graft position at the femoral condyle affects knee mobility after posterior cruciate ligament replacement

BackgroundIn some cases posterior cruciate ligament (PCL) tears require surgical reconstruction. As the femoral footprint of the ligament is quite large, an ideal graft fixation position on the medial notch wall has not yet been identified. The aim of this study was to compare three different graft fixation positions within the anatomical footprint of the PCL and test it for posterior tibial translation at different knee flexion angles.MethodsIn six human knee specimens a drawer test was simulated on a material testing machine by applying load on the tibia. At three different knee flexion angles (0°, 45°, 90°) knee mobility was examined with respect to tibial posterior translation and stiffness for the following conditions: intact ligaments, detached PCL, three different graft fixation positions on the femoral condyle.ResultsReplacement of the PCL within its femoral footprint restored knee stability in terms of tibial posterior translation. Low graft position showed comparable drawer displacements to the intact condition for all knee flexion angles (p > 0.344). A higher graft position excessively reduced the posterior translation (p < 0.047) and resulted in a restricted knee mobility and a stiffer joint.ConclusionsGraft fixation positions on the femoral condyle play a crucial role in post-operative knee mobility and joint functionality after PCL replacement. Even though all graft fixation positions were placed within the femoral footprint of a native PCL, only the lower position on the medial notch wall showed comparable posterior tibial translation to an intact PCL.     

3D CT analysis of femoral and tibial tunnel positions after modified transtibial single bundle ACL reconstruction with varus and internal rotation of the tibia

IntroductionWe analyzed the location of femoral and tibial tunnels by three-dimensional (3D) CT reconstruction images after modified transtibial single bundle (SB) anterior cruciate ligament (ACL) reconstruction, creating a femoral tunnel with varus and internal rotation of the tibia.Material and methodsData from 50 patients (50 knees) analyzed by 3D CT after modified transtibial SB ACL reconstructions were evaluated. 3D CT images were analyzed according to the quadrant method by Bernard at the femur and the technique of Forsythe at the tibia.ResultsThe mean distance of the femoral tunnel center locations parallel to the Blumensaat's line was 29.6% ± 1.9% along line t measured from the posterior condylar surface. The mean distances perpendicular to the Blumensaat's line were 37.9% ± 2.5% along line h measured from the Blumensaat's line. At the tibia, the mean anterior-to-posterior distance for the tunnel center location was 37.8% ± 1.2% and the mean medial-to-lateral distance was 50.4% ± 0.9%.DiscussionThe femoral and tibial tunnels after modified transtibial SB ACL reconstruction creating a femoral tunnel with varus and internal rotation of the tibia (figure-of-4 position) were located between the anatomical anteromedial and posterolateral footprints.     

Mechanical analysis of fixation methods for anterior cruciate ligament reconstruction with hamstring tendon graft. An experimental study in sheep knees

This study evaluates the structural properties of the femur-anterior cruciate ligament (ACL) graft-tibia complex, comparing different graft fixation techniques in sheep knees. Four fixation devices were tested both for femoral fixation (Transfix, absorbable screw, RCI screw and Linx-HT) and tibial fixation (bone plug with metal screw, absorbable screw with staple, RCI screw and cancellous screw with spiked washer). The graft used for ACL reconstruction was fresh ovine doubled Achilles tendon (DAT). Femurs and tibias were tested separately. Two mechanical test series were performed on the specimens: a load-to-failure test and a cyclic loading test. On the femoral side, transcondylar screw showed the greatest fixation strength and stiffness and the lowest elongation at cyclic loading. Tibial fixation complexes seemed to have poorer structural properties in comparison to femoral fixation. Among the tibial fixation devices, absorbable screw with staple fixation showed the greatest strength and stiffness. Spiked washer fixation showed the greatest elongation under cyclic loading.     

Morphometric side-to-side differences in human cruciate ligament insertions

Graft placement in cruciate ligament reconstruction is known to significantly influence postoperative knee stability and range of motion. Improvement of bone tunnel positioning has been advocated by computer-assisted surgical procedures that require reliable input and reference data. This study validates the hypothesis that morphometric reference data can be obtained from the uninjured controlateral knee for accurate bone tunnel and graft positioning. Thirty pairs of human cadaver knees were dissected and the femoral and tibial footprints of the anterior and posterior cruciate ligaments (PCL) were radiopaquely marked. Radiographs were taken of the corresponding left- and right-sided femora and tibiae, and digitally processed. Controlateral specimens were mirrored and overlapped precisely, the areas and intersections of ligament insertion were digitally determined. There were no significant differences in the total area of cruciate ligament insertion between left and right knee specimens or between female and male specimens. Intersection areas (IAs) in femoral and tibial anterior cruciate ligament (ACL) insertions averaged 31.3 and 33.4% of the total insertion area, respectively. The center of gravity for the femoral and tibial ACL footprint differed by 4.7 and 4.5 mm between left and right knees, respectively. IAs in femoral and tibial PCL insertions averaged 46.1 and 61.3% of the total insertion area, respectively. The center of gravity for the femoral and tibial PCL footprint differed by 4.5 and 2.4 mm between left and right knees, respectively. Our study does not support the concept of obtaining morphologic reference data from the uninjured controlateral knee for individual bone tunnel placement.     

Factors associated with revision following anterior cruciate ligament reconstruction: A systematic review of registry data

BackgroundTo identify the patient and surgical factors associated with revision anterior cruciate ligament (ACL) reconstruction as reported by all national and community ACL registries.MethodsA systematic review was performed on the MEDLINE, Embase and Cochrane Library databases. Eligibility criteria included English studies published by national or community ACL registries reporting on primary ACL reconstruction and risk factors associated with revision ACL reconstruction.ResultsThirty-three studies from the Swedish, Norwegian, Danish and Kaiser Permanente registries were included for review. Fourteen studies from all four registries reported younger age as a risk factor for revision ACL reconstruction. In addition, the Swedish registry reported concomitant medial collateral ligament (MCL) injury, undergoing earlier surgery, lower Knee Injury and Osteoarthritis Outcome Score (KOOS), smaller graft diameter and an anteromedial portal drilling technique as risk factors for revision. The risk factors reported by the Norwegian registry included lower body mass index (BMI), lower KOOS, hamstring tendon grafts and suspensory fixation. The Danish registry reported hamstring tendon grafts, anteromedial portal drilling and suspensory fixation as risk factors. The Kaiser Permanente registry reported male sex, lower BMI, ethnicity, hamstring tendon grafts, allografts, smaller graft diameter and an anteromedial portal technique as risk factors for revision.ConclusionMultiple patient and surgical factors were associated with increased risk of revision ACL reconstruction in registries. Younger age and the use of hamstring tendon grafts were consistently reported as risk factors for failure.     

Outcomes of trans-tibial posterior cruciate ligament reconstruction using a fovea landmark technique in relation to tunnel position and serial tunnel configuration

PurposeTo evaluate (1) the outcome of PCL reconstruction with tibial suspensory fixation using a fovea landmark technique based on the tunnel position and serial change of the tunnel configuration after trans-tibial PCL reconstruction, and (2) whether suspensory fixation has any harmful effect on the outcome.MethodsA total of 48 knees that underwent PCL reconstruction were included. The tunnel position was analyzed using CT. To analyze the tunnel configuration, the tunnel diameter, area, and volume were measured. To evaluate the outcome, pre- and postoperative International Knee Documentation Committee (IKDC) and Lysholm scores were analyzed. To evaluate stability, a side-to-side difference was evaluated using Telos stress radiographs.ResultsThe greatest configurational change occurred at the mid-portion of tibial tunnel. There was a correlation between stability and tibial tunnel mid-portion configurational change (p < 0.01). Important correlations were found between the tunnel position and serial tunnel configuration between high femoral tunnel and widest site of femoral tunnel and tibia aperture (p < 0.01 and 0.04, respectively). The diameter of widest site of tibia tunnel increased when the tibia tunnel center moved toward the posterior margin of the tibia (p = 0.02) and the percentage of femoral tunnel volume enlargement increased when the tibia tunnel center moved toward the medial edge of the PCL fovea (p = 0.02).ConclusionsA high femoral tunnel, medial tibial tunnel, and posterior tibial tunnel were related to the serial configurational change. A suspensory tibial fixation produced significant configurational change around the mid-portion of the tibial tunnel, and it induced a negative effect on stability.Level of Evidence: Level IV.     

The effect of anterolateral ligament reconstruction on knee constraint: A computer model-based simulation study

BackgroundTo determine the influence of anterolateral ligament reconstruction (ALLR) on knee constraint through the analysis of knee abduction (valgus) moment when the knee is subjected to external translational (anterior) or rotational (internal) loads.MethodsA knee computer model simulated from a three-dimensional computed tomography scan of healthy male was implemented for this study. Three groups were designed: (1) intact knee, (2) combined Anterior Cruciate Ligament (ACL) and Antero-Lateral Complex (ALC) deficient knee, and (3) combined ACL and Antero- lateral Ligament (ALL) reconstructed knee. The reconstructed knee group was subdivided into four groups according to attachment of reconstructed anterolateral ligament to the femoral epicondyle. Each group of simulated knees was placed at 0°, 10°, 20°, 30°, 40° and 50° of knee flexion. For each position an external anterior (drawer) 90-N force or a five-newton meter internal rotation moment was applied to the tibia. The interaction effect between the group of knees and knee flexion angle (0–50°) on knee kinematics and knee abduction moment under external loads was tested.ResultsWhen reconstructed knees were subjected to a 90-N anterior force or a five-newton meter internal rotation moment there was significant reduction in anterior translation and internal rotation compared with deficient knees. Only the ALLR procedure using posterior and proximal femoral attachment sites for graft fixation combined with ACL reconstruction allowed similar mechanical behavior to that observed in the intact knee.ConclusionsCombined ACL and ALLR using a minimally invasive method in an anatomically reproducible manner prevents excessive anterior translation and internal rotation. Using postero-proximal femoral attachment tunnel for reconstruction of ALL does not produce overconstraint of the lateral tibiofemoral compartment.     

胫骨近端关节内骨折不同植入物内固定的比较

背景：胫骨近端关节内骨折为复杂类型的关节周围骨折,其最佳植入物内固定治疗方法的选择一直是临床关注的焦点。 目的：探讨不同植入物内固定在胫骨近端关节内骨折中的应用方法和治疗效果,以选择合适的植入物内固定方法,提高治疗水平。 方法：2006年4月至2012年5月在解放军第401医院骨二科采用不同植入物内固定方式治疗胫骨近端关节内骨折合并韧带组织损伤患者41例,骨折按Schatzker分型,Ⅳ型18例,Ⅴ型12例,Ⅵ型11例;骨缺损者同时予以植骨;同时或二期行韧带组织修复,观察骨折愈合及功能恢复情况。 结果与结论：41例患者随访6-36个月,植入物内固定治疗效果参照膝关节Bristol评分标准,32-50分,平均46分,优20例,良13例,可8例,优良率80%。有29例于治疗后12-28个月取除内固定植入物。治疗方法根据不同骨折类型而选择,要做到良好复位,坚强内固定,在胫骨近端关节内骨折的植入物内固定方法选择上,采用Liss锁定钢板能给骨折端提供最大的稳定性,骨折发生轴向和侧向偏差的概率最低,并发症的发生率也最低,是最佳选择。     

Bone plug fixation in anterior cruciate ligament reconstruction: A clinical and radiological assessment of graft-tunnel integration

BackgroundThe decision regarding graft choice and fixation in anterior cruciate ligament (ACL) reconstruction remains controversial. Free cylindrical bone plugs have been used successfully as graft fixation method. However, some concerns continue to exist regarding how well these plugs integrate with the bony walls of the tunnel. The aim of this study was to assess osteo-integration of free cylindrical bone plugs and to evaluate its effect on the clinical outcomes of the procedure.MethodsFrom January 2015 to December 2017, 30 patients (21–40 years old) with torn ACL were operated on and followed up for 24 months after surgery. All patients were assessed clinically (International Knee Documentation Committee score (IKDC) and Tegner–Lysholm knee scoring system), instrumentally (KT 1000 and Rolimeter), and radiologically (X-ray, computed tomography and magnetic resonance imaging). Young active patients with torn ACL were included while those with previous ligamentous injury and/or surgery were excluded.ResultsAll bone grafts showed solid bone healing after 6 months of surgery; incorporation was ‘good to excellent’ (tibial side: 66.6%; femoral side: 86.6%). There was no correlation between age or time interval and graft incorporation. Positive correlation was shown between tibial and femoral graft incorporation within the same patient. Only one patient was abnormal in our final objective IKDC scores (graded C). The mean side-to-side difference with KT 1000 and Rolimeter was 1.9 and 1.8, respectively.ConclusionFree cylindrical bone plugs could be used safely for hamstring tendon graft fixation; it enhances graft tunnel integration within the first 6 months and yields comparable clinical outcomes whilst avoiding the potential hazards of foreign hardware implants.     

Does the anterolateral ligament protect the anterior cruciate ligament in the most common injury mechanisms? A human knee model study

BackgroundAnterior cruciate ligament (ACL) reconstruction still has a risk of re-rupture and persisting rotational instability. Thus, extra-articular structures such as the anterolateral ligament (ALL) are increasingly treated. The ALL however prevents the internal rotation of the tibia and it must be doubted that the ALL protects the ACL in other common injury mechanisms which primarily include tibial external rotation. In this study we aimed to evaluate which extra-articular structures support the ACL in excessive tibial internal and external rotation using a knee finite element (FE) model.MethodsInternal and external rotations of the tibia were applied to an FE model with anatomical ACL, posterior cruciate ligament (PCL), lateral collateral ligament (LCL), medial collateral ligament (MCL) and intact medial and lateral meniscus. Three additional anatomic structures (anterolateral ligament, popliteal tendon and posterior oblique ligament) were added to the FE model separately and then all together. The force histories within all structures were measured and determined for each case.ResultsThe ACL was the most loaded ligament both in tibial internal and external rotation. The ALL was the main stabilizer of the tibial internal rotation (46%) and prevented the tibial external rotation by only 3%. High forces were only observed in the LCL with tibial external rotation. The ALL reduced the load on the ACL in tibial internal rotation by 21%, in tibial external rotation only by 2%. The POL reduced the load on the ACL by 8%, the PLT by 6% in tibial internal rotation. In tibial external rotation the POL and PLT did not reduce the load on the ACL by more than 1%.ConclusionThe ALL protects the ACL in injury mechanisms with tibial internal rotation but not in mechanisms with tibial external rotation. In injury mechanisms with tibial external rotation other structures that support the ACL need to be considered.     

Anterior cruciate ligament graft forces are sensitive to fixation angle and tunnel position within the native femoral footprint during passive flexion

BackgroundAnterior cruciate ligament (ACL) graft position within the anatomic femoral footprint of the native ACL and the flexion angle at which the graft is fixed (i.e., fixation angle) are important considerations in ACL reconstruction surgery. However, their combined effect on ACL graft force remains less well understood.HypothesisDuring passive flexion, grafts placed high within the femoral footprint carry lower forces than grafts placed low within the femoral footprint (i.e., high and low grafts, respectively). Forces carried by high grafts are independent of fixation angle. All reconstructions impart higher forces on the graft than those carried by the native ACL.Study DesignControlled laboratory study.MethodsFive fresh-frozen cadaveric knees were mounted to a robotic manipulator and flexed from full extension to 90° of flexion. The ACL was sectioned and ACL force was calculated via superposition. ACL reconstructions were then performed using a patellar tendon autograft. For each knee, four different reconstruction permutations were tested: high and low femoral graft positions fixed at 15° and at 30° of flexion. Graft forces were calculated from full extension to 90° of flexion for each combination of femoral graft position and fixation angle again via superposition. Native ACL and ACL graft forces were compared through early flexion (by averaging tissue force from 0 to 30° of flexion) and in 5° increments from full extension to 90° of flexion.ResultsWhen fixed at 30° of flexion, high grafts carried less force than low grafts through early flexion bearing a respective 64 ± 19 N and 88 ± 11 N (p = 0.02). Increasing fixation angle from 15° to 30° caused graft forces through early flexion to increase 40 ± 13 N in low grafts and 23 ± 6 N in high grafts (p < 0.001). Low grafts fixed at 30° of flexion differed most from the native ACL, carrying 67 ± 9 N more force through early flexion (p < 0.001).ConclusionACL grafts placed high within the femoral footprint and fixed at a lower flexion angle carried less force through passive flexion compared to grafts placed lower within the femoral footprint and fixed at a higher flexion angle. At the prescribed pretensions, all grafts carried higher forces than the native ACL through passive flexion.Clinical RelevanceBoth fixation angle and femoral graft location within the anatomic ACL footprint influence graft forces and, therefore, should be considered when performing ACL reconstruction.     

Risk analysis of tunnel collision in combined anterior cruciate ligament and anterolateral ligament reconstructions

BackgroundTo assess the risk of tunnel collision in combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstructions.MethodsThree-dimensional (3D) CT reconstructions of 32 knees after transtibial (TT) (N = 16) or anteromedial portal (AMP) (N = 16) ACL reconstruction were used to simulate potential tunnel collision of the femoral ACL tunnel if combined with a virtual ALL reconstruction. The minimal distance between tunnels, the ALL tunnel length, and the lateral femoral condyle (LFC) width were measured. Moreover, the relationship between the ALL tunnel and the intercondylar notch, trochlear groove and posterior femoral cortex was determined.ResultsThe highest rate of tunnel collision (81%) was observed when the ALL tunnel was aimed at 20° in the coronal plane and 0° in the axial plane. However, by aiming the ALL tunnel at 0° coronal and 40° axial angulation, collision was avoided in all patients and no violation of the trochlea was observed. Tunnel collision rate was significantly higher (P = 0.002) when the ACL tunnel was drilled by the AMP technique.ConclusionsRisk of tunnel collision was significantly increased when the tunnel was drilled at 0° in the axial plane. Tunnel collision was avoided by aiming the ALL tunnel 40° anteriorly and perpendicular to the anatomical axis of the femur. A more horizontal orientation of the ACL with the AMP technique is a risk factor for tunnel conflicts.Clinical relevanceALL tunnel orientation needs to be adjusted to avoid tunnel conflicts in combined ACL–ALL reconstructions.     

Bioabsorbable interference screws can be used with less tunnel widening in anatomic rectangular tunnel anterior cruciate ligament reconstruction with a bone–patellar-tendon–bone graft

BackgroundThe purpose of this study was to investigate postoperative tunnel widening after rectangular tunnel bone–patellar-tendon–bone graft anterior cruciate ligament reconstruction using newer-generation bioabsorbable interference screws.MethodsForty-six patients who had undergone primary rectangular tunnel bone–patellar-tendon–bone graft anterior cruciate ligament reconstruction using MILAGRO bioabsorbable interference screws (DePuy Synthes, Warsaw, IN, USA) for femoral fixation and for whom computed tomography was performed at two weeks and one year postoperatively were included in this prospective study. To assess the tunnel widening, the cross-sectional area of the femoral tunnel aperture (compared between two weeks and one year postoperatively) was assessed using computed tomography. Cyst formation, postoperative screw breakage, screw migration, and graft migration were also evaluated using computed tomography one year postoperatively.ResultsMean tunnel widening was 1.9%, and the cross-sectional area of the femoral tunnel aperture was not significantly different between two weeks and one year postoperatively. Postoperative cyst formation, screw breakage, screw migration, and graft migration were not observed in any patient.ConclusionsAfter rectangular tunnel bone–patellar-tendon–bone graft anterior cruciate ligament reconstruction using bioabsorbable interference screws for femoral fixation, tunnel widening was not observed via computed tomography analysis at two weeks and one year postoperatively.     

Anterior cruciate ligament (ACL) repair using cortical or anchor fixation with suture tape augmentation vs ACL reconstruction: A comparative biomechanical analysis

BackgroundThe purpose was to compare knee kinematics in a cadaveric model of anterior cruciate ligament (ACL) repair using an adjustable-loop femoral cortical suspensory (AL-CSF) or independent bundle suture anchor fixation (IB-SAF) with suture tape augmentation to a bone-patellar tendon-bone (BPTB) ACL reconstruction.MethodsTwenty-seven cadaveric knees were randomly assigned to one of three surgical techniques: (1) ACL repair using the AL-CSF technique with suture tape augmentation, (2) ACL repair using the IB-SAF technique with suture tape augmentation, (3) ACL reconstruction using a BPTB autograft. Each specimen underwent three conditions according to the state of the ACL (native, proximal transection, repair/reconstruction) with each condition tested at four different angles of knee flexion (0°, 30°, 60°, 90°). Anterior tibial translation (ATT) and internal tibial rotation (ITR) were evaluated using 3-dimensional motion tracking software.ResultsACL transection resulted in a significant increase in ATT and ITR when compared to the native state (P < 0.001, respectively). ACL repair with the AL-CSF or IB-SAF technique as well as BPTB reconstruction restored native ATT and ITR at all tested angles of knee flexion, while showing significantly less ATT at 0°, 30°, 60°, and 90° as well as significantly less ITR at 30°, 60°, and 90° of knee flexion when compared to the ACL-deficient state. There were no significant differences in ATT and ITR between the three techniques utilized.ConclusionACL repair using the AL-CSF or IB-SAF technique with suture tape augmentation as well as BPTB ACL reconstruction each restored native anteroposterior and rotational laxity, without significant differences in knee kinematics between the three techniques utilized.Level of EvidenceControlled Laboratory Study.     

Characterization of collagenous and elastic fiber systems and microvasculature of human cruciate ligaments: An electronmicroscopic and stereologic study

The cruciate ligaments of 35 human knee joints were analyzed by the combined use of immunohistochemistry and transmission and scanning electron microscopy. The results were verified by morphometric analyses. The anterior cruciate ligament (ACL) had a more twisted and complex architecture compared to the posterior cruciate ligament (PCL). The PCL showed significantly (p < 0,05) thicker fibril diameters (x = 84,2 nm, s = 25,8 nm vs. x = 79,3 nm, s = 19,9 nm) and a higher total cross-sectional area (252,00 mm² vs. 208,0. 5 mm²) than the ACL. In both ligaments, type III collagen was detected using monoclonal antibodies. The ACL revealed more type VI but less type IV collagen than the PCL. The vascularization of the ACL revealed an age-dependent pattern and was significantly (p < 0,001) less well marked than in the PCL. The results reflect the poor vascular supply of the ACL in the human knee joint. The complex collagen architecture and the lower vascularization of the ACL in comparison with the PCL may contribute to poor surgical results after traumatic anterior cruciate ligament rupture. © 1993 Wiley-Liss, Inc.     

Lateral meniscal tear resulting from the femoral cross-pin used for hamstring graft fixation in anterior cruciate ligament reconstruction

We report a case of lateral meniscal tear resulting from the femoral cross-pin used for hamstring graft fixation in anterior cruciate ligament (ACL) reconstruction. A 29 year old man presented with symptoms of knee pain, catching and locking, 13 months following an ACL reconstruction. Magnetic resonance imaging (MRI) and arthroscopy confirmed the broken femoral cross-pin abutting the lateral meniscus and the resulting meniscal tear. Removal of the broken femoral cross-pin and repair of the lateral meniscal tear resulted in resolution of symptoms. Distal femoral cross-pin fracture and its intra-articular position are postulated as the cause of this lateral meniscal tear. Hence, we recommend a low threshold to investigate with a MRI scan any new symptoms following ACL reconstruction with cross-pin fixation.     

In-situ forces in the human posterior cruciate ligament in response to posterior tibial loading

Although some investigators have referred to the human posterior cruciate ligament (PCL) as the center of the knee, it has received less attention than the more frequently injured anterior cruciate ligament (ACL) and medial collateral ligament (MCL). Therefore, our understanding of the function of the PCL is limited. Our laboratory has developed a method of measuring thein-situ forces in a ligament without contacting that ligament by using a universal force-moment sensor (UFS). In this study, we attached a USF to the tibia and measuredin-situ forces of the human PCL as a function of knee flexion in response to tibial loading. At a 50-N posterior tibial load, the force in the PCL increased from 25±11 N (mean±SD) at 30° of knee flexion to 48±12 N at 90° of knee flexion. At 100 N, the corresponding increases were to 50±17 N and 95±17 N, respectively. Of note, at 30° knee flexion, approximately 45% of the resistance to posterior tibial loading was caused by contact between the tibia and the femoral condyles, whereas, at 90° of knee flexion, no resistance was caused by such contact. For direction of thein-situ force, the elevation angle from the tibial plateau was greater at 30° of knee flexion than at 90° of knee flexion. The data gathered on the magnitude and direction of thein-situ force of the PCL should help in our understanding of the dependence of knee flexion angle of the forces within the PCL.     

后外侧角股骨止点与前交叉韧带解剖重建股骨隧道外口的关系

目的 测量后外侧角（PLC）股骨止点和前交叉韧带（ACL）解剖重建股骨隧道外口的位置,以获得详细的解剖学资料,并以此为ACL和PLC一期解剖重建提供解剖依据。 方法 采用30例新鲜成人尸体膝关节标本。屈膝120°关节镜下经前内辅助入路解剖重建ACL股骨隧道,并用克氏针标记。在膝关节股骨外髁分离出膝关节外侧副韧带（LCL）和腘肌腱(PT)股骨解剖止点。以股骨外上髁为原点,建立x、y垂直坐标轴,测量LCL、PT的股骨解剖中心点和ACL股骨隧道外口在坐标轴的坐标,并测量3点之间的距离。 结果 LCL附丽部中心点在股骨外上髁近端（1.27±3.35）mm,后方（2.99±1.29）mm。PT附丽部中心点在股骨外上髁远端（8.85±3.38）mm、后方（3.83±1.95）mm。ACL股骨隧道外口在股骨外上髁近端（16.12±5.34）mm,后方（6.84±4.17）mm。LCL附丽部中心点与PT附丽部中心点相距（9.67±3.92）mm,ACL股骨隧道外口与LCL附丽部中心点相距（13.07±4.93）mm,ACL股骨隧道外口与PT附丽部中心点相距（23.37±6.16）mm。 结论 揭示了LCL、PT的股骨解剖中心点和ACL股骨隧道外口位置的解剖学特点,为临床一期联合解剖重建提供解剖学依据。