Tibiofemoral Relationship Research Articles

Temporal changes in tibiofemoral relationship following anterior cruciate ligament injury: Implications for rotational dynamics and clinical outcomes.

This study aims to elucidate changes in the tibiofemoral relationship over time following anterior cruciate ligament (ACL) injury, and investigate the correlation between the tibiofemoral relationship and patient-related outcome measures (PROMs). Overall, 203 primary ACL reconstructions were performed using autologous hamstring grafts. Medial and lateral anterior tibial translation (ATT) in the sagittal plane and tibial tubercle-trochlear groove (TT-TG) distance in the axial plane were measured using pre-operative magnetic resonance imaging and post-operative computed tomography. The difference between pre-operative and post-operative values for each parameter was calculated: ΔMesdial ATT, ΔLateral ATT and ΔTT-TG distance. The correlation between each calculated value and the time elapsed since ACL injury, and the correlation between each calculated value and PROMs-evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS)-were assessed. Sixty-four patients were enroled. Medial ATT, lateral ATT and TT-TG distance were significantly different pre-operatively compared to post-operative values, with the tibia translating anteriorly and rotating internally relative to the femur. ΔMedial ATT, ΔLateral ATT and ΔTT-TG distance were 1.6, 8.8 and -4.8 mm, respectively. A negative correlation was observed between the ΔTT-TG distance and the time elapsed since the injury (r = -0.44, p < 0.01). No correlation was found between ΔMedial ATT and the time elapsed since the injury, nor between ΔLateral ATT and the time elapsed since the injury. Neither the ΔMedial ATT, ΔLateral ATT, nor ΔTT-TG distance correlated with the pre-operative or post-operative KOOS subscale scores. The tibia underwent internal rotation relative to the femur over time following ACL injury, highlighting the importance of assessing rotational changes in ACL-injured knees. Level Ⅲ.

Tibiofemoral Relationship 3 Weeks After Anatomic Triple-Bundle Anterior Cruciate Ligament Reconstruction With 10 N of Initial Tension Is Closer to Normal Knee Versus That With 20 N of Initial Tension

PurposeThis study aimed to clarify the effect of initial graft tension on the ensuing tibiofemoral relationship and on 2-year clinical outcomes after anatomic triple-bundle anterior cruciate ligament (ACL) reconstruction. MethodsA total of 31 patients with primary unilateral ACL rupture (mean age, 25.1 years) were enrolled. Anatomic triple-bundle ACL reconstruction was performed using semitendinosus tendon autografts, and patients were grouped according to the total initial tension at graft fixation: 20 N for 16 patients between January 2012 and December 2012 and 10 N for 15 patients between January 2013 and December 2013. Three-dimensional computed tomography scans were performed preoperatively and at 3 weeks and 6 months postoperatively. The side-to-side difference of the 3-dimensional tibial position relative to the femur was compared at each time point. The side-to-side difference in anterior laxity was sequentially compared preoperatively, immediately after surgery, and at 6 months and 2 years postoperatively. Clinical outcomes at 2 years were likewise compared. ResultsOne patient in each group was excluded because of secondary ACL injury. At 3 weeks postoperatively, 2.5 ± 1.3 and 1.0 ± 1.3 mm of posterior tibial displacement and 3.8° ± 2.4° and 2.0° ± 1.7° of external rotation were observed in the 20- and 10-N initial tension groups, respectively, with significant differences (P = .006 and .033). At 6 months postoperatively, anterior displacement was 0.1/0.1 mm and external rotation was 0.8°/0.4° in both groups, without any significant differences. The 2-year clinical outcomes were satisfactory, including mean side-to-side difference in anterior knee laxity of 0.5 mm in both groups. ConclusionThe tibiofemoral relationship 3 weeks after anatomic triple-bundle ACL reconstruction with 10 N of initial tension is less constrained than that with 20 N. Six-month tibiofemoral relationship and 2-year clinical outcomes are satisfactory in both groups. Level of EvidenceIII, retrospective comparative trial

Radiographic assessment of the tibiofemoral relationship in anterior cruciate ligament deficient knees

BackgroundThe intercondylar roof line is one of the indicators used during anterior cruciate ligament (ACL) reconstruction to see the relation to the position of the tibial tunnel. The tibial tunnel can be made posteriorly in the anteriorly subluxated tibia. During ACL reconstruction, the tibiofemoral relationship of the opposite or normal knee should be considered. The purpose of this study was to examine the radiographic tibiofemoral relationship of the sagittal plane in a standing position in ACL deficient knees. MethodsIn this study, 64 patients were evaluated for inclusion. Lateral radiographs of the injured and uninjured knee were obtained preoperatively in a standing position. The knee was fully extended with the opposite foot on a step, asking the patients to bear weight fully on one leg. The tibiofemoral relationship was evaluated in the radiographs. ResultsThe mean value of anterior tibial subluxation was 1.2 mm in the injured side and −1.6 mm in the uninjured side. The tibia was located in a significantly anterior position in the injured knee (p < 0.0001). The mean distance of the space for the ACL was 9.7 mm in the injured side and 10.7 mm in the uninjured side (p < 0.01). Roof-plateau angle averaged 63.6° in the injured side and 67.4° in the uninjured side (p < 0.001). ConclusionThe tibiofemoral relationship of the ACL deficient knee was different from that of normal knee in the standing position. The relationship of the normal knee should be considered during ACL reconstruction and the risk of secondary lesions in the ACL deficient knee in activities of daily life should be considered.

The serial changes of static anterior tibial subluxation on MRI after double-bundle anterior cruciate ligament reconstruction

Objectives:Static anterior tibial subluxation after an anterior cruciate ligament (ACL) injury highlights the abnormal relationship between the tibia and femur in patients with ACL insufficiency. One of the aims of ACL reconstruction is to restore the normal tibiofemoral relationship. However, several studies indicated that an abnormal tibiofemoral relationship remained after single-bundle (SB) ACL reconstruction.The purpose of this study was to determine the serial changes of static relationship between tibia and femur in patient who had double-bundle ACL reconstruction with acute and chronic injuries.Methods:Thirty five patients who underwent double-bundle ACL reconstruction between January 1 to July 31, 2017 were included in this prospective study and divided two groups: the acute ACL injury group and the chronic ACL injury group (more than 6 month after injury). All participants underwent preoperative and postoperative magnetic resonance imaging (MRI) at 3 weeks, 3, 6 and 12 months. Anterior tibial subluxation (ATS) of the medial and lateral compartments relative to the femoral condyles were measured on MRI.Results:There were no significant differences in the age and KT side to side difference between both groups (Table 1). The ATS measurements are shown in table 2. In lateral compartment, the ATS in the acute ACL injury group was 5.3mm before surgery, while it was -0.31mm, 3.4mm, 3.5mm and 4.9mm at 3 weeks, 3, 6, 12months after surgery, respectively. The ATS in the chronic ACL injury group was 6.7mm before surgery, while it was 0.47mm, 3.9mm, 4.6mm and 5.9mm at 3 weeks, 3, 6, 12months after surgery, respectively. No significant difference was found between 2 groups.In medial compartment, the ATS in the acute ACL injury group was 1.8mm before surgery, while it was -1.6mm, 0.28mm, 0.93mm and 2.1mm at 3 weeks, 3, 6, 12months after surgery, respectively. The ATS in the chronic ACL injury group was 2.5mm before surgery, while it was -1.4mm, 1.6mm, 1.7mm and 3.0mm at 3 weeks, 3, 6, 12months after surgery, respectively. No significant difference was found between 2 groups.Conclusion:In both of lateral and medial compartment, the ATS was not significant different between acute and chronic ACL injuries before surgery. In lateral compartment, at 3 weeks, 3months and 6months after surgery, ATS was significantly less than before surgery in both groups. At 12 months, ATS was not significant different from before surgery in both groups.In medial compartment, at 3 weeks, ATS were significantly less than before surgery in both groups. After 3 months, ATS was not significant different from before surgery in both groups. The ATS was not significant different between acute and chronic ACL injuries in the same period after surgery.Figure 1.Figure 2.Figure 3.Figure 4.

Lateral Meniscus Posterior Root Lesion Influences Anterior Tibial Subluxation of the Lateral Compartment in Extension After Anterior Cruciate Ligament Injury

Background: The lateral meniscus posterior root (LMPR) lesion further decreases dynamic knee stability after anterior cruciate ligament (ACL) injury owing to the loss of the “wedge effect” maintained by the posterior horn of the lateral meniscus. However, the effect of LMPR lesions on the static tibiofemoral relationship in extension after ACL injuries is not determined. Purpose: To (1) determine the effect of LMPR lesions on anterior tibial subluxation of the lateral compartment (ATSLC) in extension in patients with ACL injuries and to (2) identify the LMPR-related factors associated with excessive ATSLC in extension. Study Design: Cohort study; Level of evidence, 3. Methods: Between January 2015 and December 2017, 405 consecutive patients with diagnosed ACL injuries who underwent primary ACL reconstructions were retrospectively reviewed. Among them, 45 patients with combined ACL injuries and LMPR lesions (ACL+LMPR group) and 51 patients with isolated ACL injuries (ACL group) were identified. Values of ATSLC in extension were measured on preoperative supine magnetic resonance imaging and classified into high grade (≥6 mm) and low grade (<6 mm). The mean ATSLC in extension and the proportion of patients with high-grade ATSLC in extension were compared between the groups by univariate analysis. In the ACL+LMPR group, predictors of high-grade ATSLC in extension—including age, sex, body mass index, affected side, cause of injury, period from injury (<12 or ≥12 weeks), LMPR lesion pattern (radial tear or root avulsion), and meniscofemoral ligament integrity (intact or impaired)—were assessed by univariate analysis and multivariate logistic regression analysis. Results: The mean ATSLC in extension in the ACL+LMPR group was significantly greater than that in the ACL group (5.6 mm vs 3.1 mm; P = .001). The proportion of patients with high-grade ATSLC in extension in the ACL+LMPR group was also significantly larger than that in the ACL group (44.4% vs 15.7%; P = .002). In addition, the root avulsion (instead of radial tear) (odds ratio, 28.750; 95% CI, 2.344-352.549; P = .009) and the period from injury ≥12 weeks (odds ratio, 17.095; 95% CI, 1.207-242.101; P = .036) were determined to be the 2 independent predictors of high-grade ATSLC in extension. However, age, sex, body mass index, affected side, cause of injury, and meniscofemoral ligament integrity were not. Conclusion: After ACL injuries, concomitant LMPR lesion further increased ATSLC in extension. Chronic LMPR avulsion was associated with high-grade ATSLC in extension.

Excessive Preoperative Anterior Tibial Subluxation in Extension Is Associated With Inferior Knee Stability After Anatomic Anterior Cruciate Ligament Reconstruction

Background: Anterior tibial subluxation (ATS) in extension after anterior cruciate ligament (ACL) injury highlights an increased anterior position of the tibia relative to the femur. Recent studies demonstrated that subluxation is sometimes irreducible and the normal tibiofemoral relationship is not restored by ACL reconstruction (ACLR), which raises concerns regarding clinical outcomes after ACLR. Hypothesis: Excessive preoperative ATS in extension is associated with inferior knee stability after anatomic ACLR. Study Design: Cohort study; Level of evidence, 3. Methods: From March 2016 to January 2017, a total of 487 consecutive patients with clinically diagnosed noncontact ACL injuries who underwent primary anatomic ACLR were retrospectively analyzed. Of these patients, 430 met the criteria for inclusion in this study. Anterior subluxation of the lateral and medial compartments (ASLC and ASMC) in extension relative to the femoral condyles was measured on preoperative magnetic resonance imaging. Twenty patients (study group) who demonstrated excessive (>10 mm) ASLC and ASMC in extension were matched 1:2 to 40 participants (control group) who showed minimal or no (<3 mm) ASLC and ASMC in extension. The amount of ASLC and ASMC in extension relative to the femoral condyles at 2 years postoperatively was the primary outcome. Moreover, the Lysholm score, IKDC grade (International Knee Documentation Committee), and stability assessments (pivot-shift test and KT-1000 arthrometer side-to-side difference) were evaluated preoperatively and at the last follow-up visit. Results: The preoperative mean ASLC and ASMC in extension of the study group were both significantly larger than those of the control group (study group vs control group: ASLC, 13.5 mm vs 1.2 mm; ASMC, 12.4 mm vs 1.0 mm; P < .05). Moreover, patients in the study group showed significantly larger posterior tibial slope than the patients in the control group (17.8°± 2.5° vs 9.5°± 1.5°; P < .05). At the final follow-up visit, the mean ASLC and ASMC of the study group were 8.1 mm and 7.3 mm, which were significantly larger than those of the control group (ASLC, 0.9 mm; ASMC, 0.7 mm; P < .05). In addition, the study group showed inferior knee stability when compared with the control group in terms of both the pivot-shift test (study group vs control group: 2 grade 2, 10 grade 1, and 8 grade 0 vs 1 grade 1 and 39 grade 0; P < .05) and the KT-1000 arthrometer side-to-side difference (study group vs control group: 4.4 ± 1.2 mm vs 1.5 ± 0.6 mm; P < .05). Furthermore, the study group showed significantly lower mean Lysholm score (study group vs control group: 80.3 ± 6.3 vs 93.3 ± 4.3, P < .05) and IKDC grading results (study group vs control group: 3 grade C, 16 grade B, and 1 grade A vs 3 grade B and 37 grade A; P < .05) as compared with the control group. Conclusion: In this short-term study, the excessive (>10 mm) preoperative ATS in extension after ACL injury was associated with inferior knee stability after anatomic ACLR.

A longitudinal tear in the medial meniscal body decreased the in situ meniscus force under an axial load.

To clarify the effect of longitudinal tears of the medial meniscus on the in situ meniscus force and the tibiofemoral relationship under axial load. Twenty-one intact porcine knees were mounted on a 6-degrees of freedom robotic system, and the force and three-dimensional path of the knee joints were recorded during three cycles under a 250-N axial load at 30°, 60°, 90° and 120° of knee flexion. They were divided into three groups of seven knees with longitudinal tears in the middle to the posterior segment of the medial meniscus based on the tear site: rim, outer one-third and inner one-third of the meniscal body. After creating tears, the same tests were performed. Finally, all paths were reproduced after total medial meniscectomy, and the in situ force of the medial meniscus was calculated based on the principle of superposition. With a longitudinal tear, the in situ force of the medial meniscus was significantly decreased at 60°, 90° and 120° of knee flexion, regardless of the tear site. The decrement was greater with a tear in the meniscal body than a tear in the rim. A longitudinal tear in the meniscal body caused a significantly greater tibial varus rotation than a tear in the rim at all flexion angles. Longitudinal tears significantly decreased the in situ force of the medial meniscus. Tears in the meniscal body caused a larger decrease of the in situ meniscus force and greater varus tibial rotation than tears in the rim.

Sequential analysis of three-dimensional tibiofemoral relationship through anatomic anterior cruciate ligament reconstruction with gravity-assisted radiographic technique in prone position

Background/objectivesIt is important to restore the tibiofemoral relationship as well as the anterior knee laxity for more successful anterior cruciate ligament (ACL) reconstruction, since a residual abnormality in the tibiofemoral relationship would lead an abnormal stress on the articular cartilages/menisci and consequently increase the risk of osteoarthritis in the future. This study aimed to sequentially clarify the three-dimensional tibiofemoral relationship before and after anatomic anterior cruciate ligament (ACL) reconstruction under an anterior tibial load with a gravity-assisted radiographic technique in the prone position. MethodsFifteen patients with unilateral ACL injury participated in the study. Anatomic triple-bundle ACL reconstruction was performed using semitendinosus tendon autografts. During the computed tomography scans that were performed preoperatively, and those performed at 3 weeks and at 6 months postoperatively, the patients lay in the prone position with the knee flexed at 15°, wherein the calf weight could exert an anterior drawer force on the tibia due to gravity. Three-dimensional the tibial position relative to the femur were evaluated for each time point, followed by calculation of side-to-side differences in the parameters between the ACL-deficient/ACL-reconstructed knees and the contralateral intact knees. Seven healthy volunteers were enrolled in the control group and the side-to-side differences (right minus left) in these parameters were calculated. ResultsThe tibia in the ACL-deficient knee was located anteriorly by 3.5 ± 1.1 mm and rotated internally by 2.4° ± 2.3°; these values were significantly larger than the corresponding values of −0.2 ± 1.5 mm and 0.1° ± 2.2° in the control group. However, at 3 weeks postoperatively, the tibia in the ACL-reconstructed knee was over-constrained as compared to that in the control group; it was located posteriorly by 2.5 ± 1.4 mm and rotated externally by 3.4° ± 3.4°. At 6 months postoperatively, no significant difference was observed in the tibial displacements/rotations between the patient and control groups. The side-to-side difference in the anterior knee laxity at the manual maximum anterior load was 0.1 ± 1.2 mm at 6 months postoperatively, with a significant improvement over the preoperative value of 7.4 ± 2.5 mm. ConclusionsAnatomic ACL reconstruction could restore not only the normal anterior knee laxity, but also the normal tibiofemoral relationship even under an anterior tibial load.

Early Structural Results After Anatomic Triple Bundle Anterior Cruciate Ligament Reconstruction Validated by Tunnel Location, Graft Orientation, and Static Anteroposterior Tibia-Femur Relationship

To elucidate how closely the structural characteristics of the anterior cruciate ligament (ACL) grafts after anatomic triple bundle (ATB) reconstruction resembled those of the normal ACL. From 2012 to 2016, patients who underwent primary ATB ACL reconstruction using hamstring tendon autografts and the same number of healthy control subjects were included. Using magnetic resonance imaging (MRI) taken at 6months postoperatively, ACL graft orientation was evaluated by the angles against the tibial plateau measured in the sagittal and oblique coronal planes at the anteromedial and posterolateral portions (ACL-tibial plateau angle [ATA]). For factors affecting the graft orientation, the static tibiofemoral relationship was evaluated by anteroposterior tibial translocation (APTT) in the identical MRI using a previously established method, and tunnel locations were evaluated using the quadrant method. To test equivalence, the widely used two one-sided test procedure was performed, with the equivalence margins of 5° and 3mm for ATA and APTT, respectively. Thirty-five patients were enrolled for each group. ATAs were not significantly different, and the 95% confidence interval (CI) of these differences was within 5° (sagittal: P= .211 [95% CI,-2.9 to 0.6]; oblique coronal ATA for the anteromedial and posterolateral portions: P= .269 [95% CI,-1.9 to 0.5] and P= .456 [95% CI,-2.1 to 0.9], respectively). The difference in APTT was neither statistically nor clinically significant (P= .114; 95% CI,-2.0 to 0.2). These data suggest that ACL grafts using the ATB technique achieved a graft orientation equivalent to that of the normal ACL, with an equivalent postoperative anteroposterior tibiofemoral relationship in the static MRI. Thus, the ATB ACL reconstruction technique with the presented tunnel locations produced grafts that were similar to the native ACL in orientation. Level III, case-control study.

Chronicity of Anterior Cruciate Ligament Deficiency, Part 2: Radiographic Predictors of Early Graft Failure.

Background:Accumulating evidence suggests that long-term anterior cruciate ligament (ACL) deficiency can give rise to an abnormal tibiofemoral relationship and subsequent intra-articular lesions. However, the effects of chronic ACL deficiency (ACLD) on early graft failure after anatomic reconstruction remain unclear.Hypothesis:We hypothesized that patients with long-term ACLD lasting more than 5 years would have a greater rate of early graft failure due to insufficient intraoperative reduction of the tibia and that the preoperative and immediately postoperative abnormal tibiofemoral relationship in the sagittal plane, such as anterior tibial subluxation (ATS), would correlate with the graft status on postoperative magnetic resonance imaging (MRI).Study Design:Cohort study; Level of evidence, 3.Methods:A total of 358 patients who had undergone anatomic ACL reconstruction with hamstring grafts were divided into 5 groups based on chronicity of ACLD: (1) 0 to 6 months, (2) 6 months to 1 year, (3) 1 to 2 years, (4) 2 to 5 years, and (5) longer than 5 years. Preoperatively and immediately postoperatively, lateral radiographs in full extension were taken in all patients to evaluate the tibiofemoral relationship, specifically with regard to ATS, space for the ACL (sACL), and extension angle. All patients underwent MRI at 6 months to reveal graft status. Groups with a high rate of graft failure were further analyzed to compare demographic and radiographic factors between the intact and failure subgroups, followed by multivariate logistic regression analysis to identify predisposing factors.Results:Graft failure without trauma was observed in 4 (1.8%), 0 (0%), 1 (3.7%), 3 (9.7%), and 8 patients (17.7%) in groups 1, 2, 3, 4, and 5, respectively. Of the 76 patients in groups 4 and 5, significant differences were noted between the failure and intact subgroups in preoperative ATS (4.9 vs 2.4 mm, respectively; P < .01), side-to-side differences in sACL (sACL-SSD) (4.7 vs 1.9 mm, respectively; P < .01), extension deficit (4.4° vs 1.3°, respectively; P < .01), and chondral lesions (P = .02), while postoperative ATS and sACL-SSD showed no differences. Multivariate logistic regression analysis revealed that of these factors, preoperative sACL-SSD could be a risk factor for early graft failure (odds ratio, 3.2; 95% CI, 1.37-7.46).ConclusionEarly graft failure at 6 months increased in patients with ACLD longer than 2 years. In this population, preoperative sACL-SSD was the most significant risk factor for early graft failure on MRI. However, immediately postoperative radiographic measurements had no effect on graft failure rates.

Chronicity of Anterior Cruciate Ligament Deficiency, Part 1: Effects on the Tibiofemoral Relationship Before and Immediately After Anatomic ACL Reconstruction With Autologous Hamstring Grafts.

Background:It remains unclear whether the tibiofemoral relationship in the sagittal plane is restored after anatomic anterior cruciate ligament (ACL) reconstruction, particularly in cases of chronic ACL deficiency (ACLD).Hypothesis:Patients with long-term ACLD will exhibit an anteriorly subluxed tibia both preoperatively and immediately postoperatively, even after anatomic reconstruction.Study Design:Cohort study; Level of evidence, 2.Methods:In total, 358 patients who had undergone anatomic ACL reconstruction with autologous semitendinosus grafts were divided into 5 groups based on chronicity of ACLD: (1) 0 to 6 months, (2) 6 months to 1 year, (3) 1 to 2 years, (4) 2 to 5 years, and (5) longer than 5 years. Preoperatively and immediately postoperatively, all patients underwent lateral radiography in extension to evaluate the tibiofemoral relationship, specifically with regard to anterior tibial subluxation (ATS), space for the ACL (sACL), and extension angle. Demographic and radiographic factors were compared among the 5 groups.Results:Preoperative ATS values in groups 4 (mean ± SD, 2.9 ± 2.1 mm) and 5 (2.6 ± 1.9 mm) were significantly greater than in group 1 (1.6 ± 1.9 mm). Postoperatively, the tibia was posteriorly overconstrained in all groups, and there was no difference in immediately postoperative ATS among the 5 groups. Further evaluation of the tibiofemoral relationship in the sagittal plane revealed that the mean preoperative side-to-side difference in sACL (sACL-SSD) was greater in groups 4 (2.5 ± 1.6 mm) and 5 (2.2 ± 1.7 mm) than in group 1 (1.2 ± 1.5 mm). Immediately after ACL reconstruction, however, there were no group-dependent differences in sACL-SSD. No significant group-dependent differences were found for extension deficit.Conclusion:Chronicity of ACLD had an effect on the preoperative tibiofemoral relationship in the sagittal plane, including ATS and sACL-SSD, especially in patients with ACLD longer than 2 years. However, preoperative extension deficit was not influenced by chronicity. Immediately postoperatively, chronicity did not affect the ability of anatomic ACL reconstruction to reduce subluxation.

Effect of radial meniscal tear on in situ forces of meniscus and tibiofemoral relationship.

To clarify the effect of the radial tear of the lateral meniscus on the in situ meniscus force and the tibiofemoral relationship under axial loads and valgus torques. Ten intact porcine knees were settled to a 6-degree of freedom robotic system, while the force and 3-dimensional path of the knees were recorded via Universal Force Sensor (UFS) during 3 cycles of 250-N axial load and 5-Nm valgus torque at 15°, 30°, 45°, and 60° of knee flexion. The same examination was performed on the following 3 meniscal states sequentially; 33, 66, and 100% width of radial tears at the middle segment of the lateral meniscus, while recording the force and path of the knees via UFS. Finally, all paths were reproduced after total lateral meniscectomy and the in situ force of the lateral meniscus were calculated with the principle of superposition. The radial tear of 100% width significantly decreased the in situ force of the lateral meniscus and caused tibial medial shift and valgus rotation at 30°-60° of knee flexion in both testing protocols. Under a 250-N axial load at 60° of knee flexion, the in situ force decreased to 36±29N with 100% width of radial tear, which was 122±38N in the intact state. Additionally, the tibia shifted medially by 2.1±0.9mm and valgusrotated by 2.5±1.9° with the complete radial tear. However, the radial tear of 33 or 66% width had little effect on either the in situ force or the tibial position. A radial tear of 100% width involving the rim significantly decreased the in situ force of the lateral meniscus and caused medial shift and valgus rotation of the tibia, whereas a radial tear of up to 66% width produced only little change. The clinical relevance is that loss of meniscal functions due to complete radial tear can lead to abnormal stress concentration in a focal area of cartilage and can increase the risk of osteoarthritis in the future.

Influence of initial tension on the postoperative tibiofemoral relationship after anatomic anterior cruciate ligament reconstruction

Influence of initial tension on the postoperative tibiofemoral relationship after anatomic anterior cruciate ligament reconstruction

Tibiofemoral relationship following anatomic triple-bundle anterior cruciate ligament reconstruction

The purpose of this study was to investigate the tibiofemoral relationship sequentially before and after anatomic triple-bundle (TB) anterior cruciate ligament (ACL) reconstruction in the same patients. Nine patients with complete unilateral ACL rupture participated in this study. Anatomic TB ACL reconstruction was performed using autogenous semitendinosus tendon grafts. Computed tomography images were obtained before surgery as well as 3weeks and 6months afterwards. During image acquisition, the patient's knees were fully extended in the supine position. Using three-dimensional computer models, anterior-posterior and medial-lateral displacement of the tibia relative to the femur were evaluated for each period, as were internal-external and varus-valgus rotation, followed by calculation of side-to-side differences in parameters. As the control group, 7 healthy volunteers were evaluated. The tibia was located anteriorly by 1.4±0.9mm and rotated internally by 2.1±1.7° before surgery, while the tibia was located posteriorly by 2.0±1.2mm and rotated externally by 3.4±3.5° 3weeks after surgery. Six months after surgery, there was no significant difference between the patient and control groups. The anteriorly located and internally rotated tibia in ACL-deficient knees was over-constrained (posterior displacement and external rotation) 3weeks after anatomic TB ACL reconstruction, but returned to the normal position 6months afterwards. Therefore, anatomic tunnel placement, appropriate initial tension, and moderate rehabilitation can be the key for return to the normal tibiofemoral relationship after ACL reconstruction. Therapeutic study, Level IV.

Passive Anterior Tibial Subluxation in Anterior Cruciate Ligament–Deficient Knees

Background: Abnormal anterior-posterior and rotational motion secondary to anterior cruciate ligament (ACL) insufficiency is typically described in terms of dynamic laxity. An original description of the abnormal tibiofemoral relationship in the setting of ACL insufficiency has highlighted the presence of a fixed anterior tibial subluxation in this population of failed ACL reconstruction (ACLR); however, no study has quantified the degree of tibial subluxation in both the medial and lateral compartments. Purpose: To measure and compare the amount of anterior tibial subluxation among various states of ACL competency, including (1) intact ACL, (2) acute ACL disruption, and (3) failed ACLR (ie, patients requiring revision ACLR). We hypothesized that anterior tibial displacement would be greater in the lateral compartment and in cases of failed ACLR compared with intact and acute ACL injured states. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Using sagittal magnetic resonance imaging (MRI) and a standardized measurement technique, we determined the amount of anterior tibial subluxation relative to a constant posterior condylar reference point. Measurements were performed in both the medial and the lateral compartments and were compared with 1-way analysis of variance. The presence of meniscal tears along with meniscal volume loss and chondral damage was correlated with the amount of subluxation in each group. Results: Compared with the intact ACL state, the medial tibial plateau was positioned more anteriorly relative to the femur in both acute ACL injured knees (mean 1.0 mm) and those that failed ACLR (mean 1.8 mm) (P = .072). In the lateral compartment, there was 0.8 mm of mean anterior tibial displacement after acute ACL injury and 3.9 mm of mean anterior subluxation in patients who failed ACLR (P < .001). Mean anterior displacement of the lateral plateau in patients who failed ACLR was almost 5 times greater than the amount observed in patients with acute ACL injuries. There was no correlation between meniscal/chondral injury and the amount of subluxation. Conclusion: Patients who require revision ACLR have an abnormal tibiofemoral relationship noted on MRI that is most pronounced in the lateral compartment and should be taken into account during revision surgery. These observations may explain the suboptimal clinical results seen in some patients who undergo revision ACLR.

Paper # 224: The Effect of PCL on Kinematic and Clinical Results of Ultracongruent Mobile TKA

The PCL-preserving ultracongruent mobile TKA showed more potentially vulnerable intraoperative kinematics and two serious complications, compared with the PCL-sacrificing TKA. There is a concern that patients who have undergone posterior cruciate ligament(PCL)-preserving ultracongruent mobile total knee arthroplasty(TKA) that does not have a cam and post mechanism can improve the kinematics, stability and clinical outcome, compared with PCL-sacrificing TKA. We aimed to evaluate the effect of PCL on kinematics and clinical results of UC mobile TKA. Ninety knees with primary osteoarthritis were randomly allocated to Group P(PCL-preserving UC RP TKA) or Group S(PCL-sacrificing UC RP TKA). Passive intraoperative kinematics was recorded by navigation system immediately after implantation. Three parameters of tibiofemoral relationship(anterior/posterior translation, varus/valgus rotation, internal/external rotation) were analyzed in both groups from 10° to 120° of flexion. The range of motion, functional scores, radiographic results and complications were also evaluated. The minimally follow up period was 2 years postoperatively. There were significant differences in the varus/valgus rotation and anterior/posterior translation of the femur. Group P(42knees) had more varus rotation over 90° flexion(p<0.05) and more anterior translation of the femur in all range of flexion(p<0.05) than group S(44knees). There was no difference in internal/external rotation of the femur(p>0.05). The range of motion was not different at final follow up(125° vs 120°, p=0.178). Functional scores and radiographic results were not different between two groups. Two knees in Group P were revised: one presented with posterior instability by attenuated PCL at 7 weeks after surgery and treated with exchange into thicker insert; the other with insert subluxation over 120° flexion at 1 week treated with resection of tight PCL and thicker insert. PCL-preserving ultracongruent mobile TKA showed not only the significant deviation in kinematics including anterior translation of the femur and varus rotation but also unpredictable complications including instability and subluxation, compared with PCL-sacrificing ultracongruent mobile TKA. It is recommended to remove PCL and get well balanced gap and stability independent of PCL at initial surgery in ultracongruent TKA.

Analysis of Weight-Bearing Kinematics of Posterior-Stabilized Total Knee Arthroplasty With Novel Helical Post-Cam Design

We developed a new posterior-stabilized total knee arthroplasty (TKA) with a unique post-cam design that induces and accommodates internal tibial rotation with deep knee flexion. To validate the design concept of this system, we conducted an image analysis study employing a computer-aided diagnosis system for 24 TKA-implanted knees. In the analysis, the tibiofemoral relationship in the following 3 postures was evaluated: standing at extension, forward lunge, and kneeling with maximum knee flexion. The results of the image analysis showed achievement of consistent internal rotation of the tibia in deep flexion with a broad contact area at the post-cam interface as intended by the original design concept of this TKA system.

Tibiofemoral Kinematics following Successful Anterior Cruciate Ligament Reconstruction Using Dynamic Multiple Resonance Imaging

Background The aim of anterior cruciate ligament reconstruction is to reduce excess joint laxity, hoping to restore normal tibiofemoral kinematics and therefore improve joint stability. It remains unclear if successful ACL reconstruction restores normal tibiofemoral kinematics and whether it is this that is associated with a good result. Study Case series. Purpose To assess the kinematics of the anterior cruciate ligament-reconstructed knee using open-access MRI. Methods Tibiofemoral motion was assessed using open-access MRI, weightbearing through the arc of flexion from 0° to 90° in 10 patients with isolated reconstruction of the anterior cruciate ligament (hamstring autograft) in one knee and a normal contralateral knee. Midmedial and midlateral sagittal images were analyzed in all positions of flexion in both knees to assess the tibiofemoral relationship. Sagittal laxity was also assessed by performing the Lachman test while the knees were scanned dynamically using open-access MRI. Results The amount of excursion between the tibial and femoral joint surfaces was similar between the normal and reconstructed knees, but the relationship of tibia to femur was always different for each position of knee flexion assessed—the lateral tibia being about 5 mm more anterior in the anterior cruciate ligament-reconstructed knees. This anterior tibial position is statistically significantly different at 0° (P < .0006), 20° (P = .0004), 45° (P = .002), and 90° of flexion (P < .006). Anteroposterior laxity was similar between normal and anterior cruciate ligament-reconstructed knees. Conclusion Anterior cruciate ligament reconstruction reduces sagittal laxity to within normal limits but does not restore normal tibiofemoral kinematics despite a successful outcome.

Knee stability following anterior cruciate ligament rupture and surgery. The contribution of irreducible tibial subluxation.

Knee stability after anterior cruciate ligament reconstruction is generally determined by measuring total anteroposterior tibial motion. In spite of a decrease in excessive anteroposterior tibial motion after anterior cruciate ligament reconstruction, problems can still develop. In the present study, we sought to define the tibiofemoral relationship more accurately with use of stress radiographs of human knees after anterior cruciate ligament rupture and after anterior cruciate ligament reconstruction. A previously described radiographic technique was used to evaluate the position of the tibia relative to the femur with the application of an anteriorly directed tibial force and subsequently with the application of a posteriorly directed tibial force. Tibial position and total tibial translation were calculated from these radiographs. In addition, KT-1000 measurements were obtained. Three groups of patients were studied: Group 1 included twenty-eight patients with an untreated anterior cruciate ligament rupture, Group 2 included nineteen patients who had undergone a clinically successful anterior cruciate ligament reconstruction, and Group 3 included twenty-five control subjects with normal knees. KT-1000 testing showed that the average side-to-side differences in Group 1 (5.8 mm) and Group 2 (2.7 mm) were significantly different from that in Group 3 (0.8 mm) (p < 0.01 and p < 0.05, respectively). Stress radiographs showed that the average total tibial translation in Group 1 (9.8 mm) was significantly different from those in Group 2 (5.6 mm) and Group 3 (4.3 mm) (p < 0.05 and p < 0.001, respectively). Within Group 1, knees with radiographic signs of osteoarthritis were more stable, with an average total tibial excursion of 6.8 mm. The improved stability of the reconstructed knees in Group 2 and the osteoarthritic knees in Group 1 was not entirely the result of decreased anterior tibial translation; it was, in part, due to an irreducible anterior subluxation of the tibia. A posteriorly directed stress in these knees did not reduce the tibia to the anatomic position relative to the femur; the osteoarthritic knees in Group 1 were 9.9 mm short of full reduction and the knees in Group 2 were 3.1 mm short of full reduction (p < 0.01) Irreducible tibial subluxation can be present in the knee following surgical reconstruction of the anterior cruciate ligament. Osteoarthritic changes following an untreated anterior cruciate ligament rupture are also associated with uncorrectable tibial subluxation along with a decrease in instability. The irreducible tibial subluxation could explain why osteoarthritic changes still may develop in stable, reconstructed knees in spite of the improved stability. Currently used arthrometric measurements, such as KT-1000 scores, do not measure this phenomenon.

Tibiofemoral Kinematics of the Anterior Cruciate Ligament (ACL)-Deficient Weightbearing, Living Knee Employing Vertical Access Open “Interventional” Multiple Resonance Imaging

Background Our current understanding of tibiofemoral kinematics in the anterior cruciate ligament (ACL)-deficient knee is very limited. Using vertical open-access MRI, it is possible to accurately analyze tibiofemoral motion in patients with isolated rupture of the ACL. Study Prospective cohort study. Purpose To assess if ACL rupture alters normal knee weightbearing kinematics. Methods Tibiofemoral motion was assessed through the arc of flexion from 0 ° to 90 ° in 10 patients with isolated rupture of the ACL in one knee and a normal contralateral knee. Midmedial and midlateral sagittal images were analyzed in all positions of flexion in both knees to assess the tibiofemoral relationship. Results In the lateral compartment of the knee, the tibial plateau is persistently subluxed anteriorly throughout the arc of flexion from 0 ° to 90 ° (flexion facet center to posterior tibial cortex distance of 15.8 mm ± 2.9 in ACL-deficient knees compared to 21.4 mm ± 1.4 in normal knees at 0 ° extension, P< .0001) when compared to normal knees. The medial tibiofemoral relationship is unchanged compared to normal knees. Conclusion Rupture of the ACL changes tibiofemoral kinematics producing anterior subluxation of the lateral tibial plateau. Clinical Significance Altered kinematics may explain, at least in part, the increased incidence of secondary osteoarthritis in patients with ACL rupture.