Pivot Shift Phenomenon Research Articles

Knee hyperextension and a small lateral condyle are associated with greater quantified antero-lateral rotatory instability in the patients with a complete anterior cruciate ligament (ACL) rupture.

To identify factors associated with quantified rotatory stability (pivot-shift phenomenon) in the anterior cruciate ligament (ACL)-injured knee joint. A consecutive sample of 54 patients who were diagnosed with an ACL injury and admitted to our hospital to undergo ACL reconstruction were enrolled in this study. Antero-lateral rotatory laxity of the knee joint was quantified using a Kinematic Rapid Assessment device (KiRA; Orthokey LTD) under spinal block before initiating reconstruction of the ACL. Univariate and multivariate regressions were performed assuming relationships between patient characteristics (independent variables) and quantified antero-lateral rotatory stability (a dependent variable). It was observed that a low BMI (t = - 1.659, n.s.), greater passive knee extension angle (t = 2.374, P = 0.023), and a narrower lateral femoral condyle width index (t = - 1.712, n.s.) could be candidates associated with the antero-lateral rotatory instability, using univariate analysis. Employing multivariate analysis controlling for these three variables, that the range of passive knee extension was found to be significantly associated with antero-lateral rotatory instability in the ACL-injured knee joint (t = 2.21, P = 0.035). Patients were then divided into two groups (pivot-shift negative versus positive groups) based on the KiRA-documented quantified pivot-shift test. Interestingly, 23.3% of patients were pivot-shift negative, even though their ACL was confirmed as a complete rupture by arthroscopic observations. The degree of passive knee extension was 2.3 ± 4.5 (mean ± SD) in the pivot-shift negative group, while it was 6.8 ± 6.6 in the pivot-shift positive group (n.s.). The lateral femoral condyle width index was 36.6 ± 2.0% in the pivot-shift negative group, and it was significantly wider than in the pivot-shift positive group (33.8 ± 2.6%, P = 0.0046). Finally, we estimated that the risk of positive pivot-shift depends on the degree of knee extension. The logistic regression analysis revealed that genu recurvatum significantly increased the odds ratio for positive pivot-shift (OR = 3.08, P = 0.047, 95% CI = 1.017-9.350). This study revealed that greater antero-lateral rotatory instability in patients with a complete ACL rupture was associated with genu recurvatum and small lateral femoral condyle. These factors should be considered as predictors of a poor outcome from an ACL reconstruction due to a higher load on the ACL graft, and therefore, the attending physicians should modify the treatment strategies accordingly. This study indicates that joint hyperlaxity and bone morphology contribute to the rotational stability of the knee joint, in addition to the ACL and antero-lateral complex (ALC). IV.

Modified Lemaire extra-articular stabilisation of the knee for the treatment of anterolateral instability combined with diffuse pigmented villonodular synovitis: a case report

BackgroundDiffuse pigmented villonodular synovitis (PVNS) of the knee is a rare proliferative joint disease associated with high recurrence rates following surgical treatment. Intra-articular joint instability in conjunction with PVNS implies complex reconstructive strategies due to the destructive nature of the disease.Case presentationHere, we present the case of a young patient with refractory PVNS and a chronic ipsilateral anterior cruciate ligament (ACL) rupture. Clinically, the patient presented with a grade 3 pivot shift phenomenon, indicating anterolateral rotational instability. Usually, PVNS implies a contraindication for ACL reconstruction due to the degenerative and pro-inflammatory joint microenvironment that is induced and maintained by PVNS. Therefore, we have performed a modified Lemaire extra-articular stabilization resulting in significant clinical improvement and subjective joint stability. In the latest follow-up examination at 12 months, the patient reported subjective joint stability and no swelling. In the clinical examination, the patient showed dynamic joint stability during walking. Additionally, the patient presented with grade 0 in pivot-shifting compared to the contralateral knee. The Lachman test exhibited no increased side-to-side difference and a firm endpoint.ConclusionsExtra-articular anterolateral stabilisation of the knee in patients having anterolateral knee instability combined with PVNS is a safe and efficient surgical treatment option yielding significant clinical improvement as well as subjective joint stability.

Partial Anterior Cruciate Ligament Ruptures: Advantages by Intraligament Autologous Conditioned Plasma Injection and Healing Response Technique-Midterm Outcome Evaluation.

The historical treatment options for partial anterior cruciate ligament (ACL) ruptures were conservative therapy or ACL reconstruction by injured bundle or entire ACL replacement. In awareness of the regenerative potential of biologic agents such as mesenchymal stem cells or platelet rich plasma (PRP), the healing response technique was developed to preserve the injured ACL with better outcomes than the conservative therapy. Further improvement of this technique seems to be obtained by the additional application of PRP products. Thus, the aim of this study was to evaluate the midterm outcome after intraligament autologous conditioned plasma (ACP) by a clinical, scoring, and functional performance assessment. 42 patients were evaluated in this study. The failure rate was 9.5%. Outcome evaluation showed good to excellent results. The scores were IKDC subjective 83.2 (SD 14.5), Lysholm 85.5 (SD 15.5), Tegner 4.7 (SD 1.7), and Cincinnati 85.4 (SD 15.5) after a mean follow-up of 33 months. Clinical examination showed stable Lachman test, negative pivot shift phenomenon, and a significant reduction in AP-laxity compared to preoperative status (rolimeter preoperative: 1.9 (SD1.4); postoperative 0.6 (SD1.8), p=0.001) in all patients. Functional performance testing showed no significant differences between the injured and healthy side. Return to sport was achieved after a mean of 5.8 months (SD 3.6) in 71.1% of the included patients. In summary, this new treatment option revealed in midterm follow-up promising results to treat partial ACL lesions with a reduced need for conversion to ACL reconstruction and with a high percentage of return to preinjury sport activity.

Effect of Meniscocapsular and Meniscotibial Lesions in ACL-Deficient and ACL-Reconstructed Knees: A Biomechanical Study

Background: Ramp lesions were initially defined as a tear of the peripheral attachment of the posterior horn of the medial meniscus at the meniscocapsular junction. The separate biomechanical roles of the meniscocapsular and meniscotibial attachments of the posterior medial meniscus have not been fully delineated. Purpose: To evaluate the biomechanical effects of meniscocapsular and meniscotibial lesions of the posterior medial meniscus in anterior cruciate ligament (ACL)–deficient and ACL-reconstructed knees and the effect of repair of ramp lesions. Study Design: Controlled laboratory study. Methods: Twelve matched pairs of human cadaveric knees were evaluated with a 6 degrees of freedom robotic system. All knees were subjected to an 88-N anterior tibial load, internal and external rotation torques of 5 N·m, and a simulated pivot-shift test of 10-N valgus force coupled with 5-N·m internal rotation. The paired knees were randomized to the cutting of either the meniscocapsular or the meniscotibial attachments after ACL reconstruction (ACLR). Eight comparisons of interest were chosen before data analysis was conducted. Data from the intact state were compared with data from the subsequent states. The following states were tested: intact (n = 24), ACL deficient (n = 24), ACL deficient with a meniscocapsular lesion (n = 12), ACL deficient with a meniscotibial lesion (n = 12), ACL deficient with both meniscocapsular and meniscotibial lesions (n = 24), ACLR with both meniscocapsular and meniscotibial lesions (n = 16), and ACLR with repair of both meniscocapsular and meniscotibial lesions (n = 16). All states were compared with the previous states. For the repair and reconstruction states, only the specimens that underwent repair were compared with their intact and sectioned states, thus excluding the specimens that did not undergo repair. Results: Cutting the meniscocapsular and meniscotibial attachments of the posterior horn of the medial meniscus significantly increased anterior tibial translation in ACL-deficient knees at 30° (P ≤ .020) and 90° (P < .005). Cutting both the meniscocapsular and meniscotibial attachments increased tibial internal (all P > .004) and external (all P < .001) rotation at all flexion angles in ACL-reconstructed knees. Reconstruction of the ACL in the presence of meniscocapsular and meniscotibial tears restored anterior tibial translation (P > .053) but did not restore internal rotation (P < .002), external rotation (P < .002), and the pivot shift (P < .05). To restore the pivot shift, an ACLR and a concurrent repair of the meniscocapsular and meniscotibial lesions were both necessary. Repairing the meniscocapsular and meniscotibial lesions after ACLR did not restore internal rotation and external rotation at angles >30°. Conclusion: Meniscocapsular and meniscotibial lesions of the posterior horn of the medial meniscus increased knee anterior tibial translation, internal and external rotation, and the pivot shift in ACL-deficient knees. The pivot shift was not restored with an isolated ACLR but was restored when performed concomitantly with a meniscocapsular and meniscotibial repair. However, the effect of this change was minimal; although statistical significance was found, the overall clinical significance remains unclear. The ramp lesion repair used in this study failed to restore internal rotation and external rotation at higher knee flexion angles. Further studies should examine improved meniscus repair techniques for root tears combined with ACLRs. Clinical Relevance: Meniscal ramp lesions should be repaired at the time of ACLR to avoid continued knee instability (anterior tibial translation) and to eliminate the pivot-shift phenomenon.

Intra-ligamentary autologous conditioned plasma and healing response to treat partial ACL ruptures.

Conservative treatment of partial ACL ruptures is associated with a high failure rate, and often patients undergo ACL reconstruction. ACL preservation by trephination of the ACL origin and application of Autologous Conditioned Plasma (ACP) seems to be an intriguing new treatment option to favour ACL tissue healing and avoid traditional reconstruction. The aim of this study was to describe the mid-term outcomes of this new ACL preserving technique. Twenty-four patients (mean age 41.8years) affected by partial rupture of one or both ACL bundles were included in the present trial. The partial ACL tears were arthroscopically assessed and classified according to a new five step grading system. All patients were treated by trephination of the femoral ACL stump and intra-ligamentary application of ACP. The postoperative outcome was evaluated by both subjective scores and stability testing up to a mean of 25.1 months' follow-up. Adverse events and failure rate were also documented. Clinical outcome was good to excellent with IKDC subjective 82.7 (SD 11.8), Lysholm 87.6 (SD 8.1), Tegner 5.3 (SD 2.1), Cincinnati 88.7 (SD 14.8). The failure rate (i.e. persisting knee instability assessed clinically or by rolimeter) was 12.5%. At objective measurements, knee joints showed a firm endpoint in Lachman test, negative pivot shift phenomenon and a significant reduction in AP-laxity compared to pre-operative status by rolimeter testing (p = 0.002). Return to sport practice was achieved after mean 4.8 months (SD 4.1). ACL stump trephination and concomitant intra-ligamentary application of ACP revealed promising results at mid-term follow-up to treat partial ACL lesions.

Utility of a New Developed Motion Capture with Infrared Camera System in ACL-Insufficient Knees by the Comparison with the Validated Navigation System

Based on the quantification of a dynamic rotatory knee laxity reproduced and evaluated by the pivot-shift test, our newly developed noninvasive system (MCICS) could be as accurate as the validated navigation system, particularly within range of knee flexion during the pivot-shift test, which could be useful in diagnosis of ACL pathology and the postoperative evaluation of surgical reconstruction. Development of more objective clinical evaluation of the rotational instability in the ACL - insufficient knee is critical to evaluate its function extensively and to improve the outcome in the ACL reconstructive surgery. However, there are few available quantitative methods for the rotational instability in a clinical use. We have developed a new noninvasive motion capture with infrared camera system (MCICS; Anima Co. Ltd.,Tokyo, Japan) for analysis of in vivo three-dimensional kinematics of the knee. The purpose of this study are to compare our MCICS with the standard validated commercial navigation system in terms of reliability and repeatability of the rotational kinematics in the ACL-insufficient knee, and to validate the utility of our MCICS. Thirteen unilateral ACL injured patients (mean age 18 y.o.) were enrolled in this study. The injured knees in all patients were evaluated during the pivot shift test by a single surgeon (E.N.) before reconstruction under anesthesia using two imaging equipment; one is a commercial image-free navigation system (Brain Lab, ACL 2.0, Heirnstettern, Germany) with trackers secured by bone screws (Navi), and the other is our MCICS. During the pivot-shift test, the starting angle of the pivot-shift phenomenon (SA; °), and tibial rotational angle defined as the amount of rotational angle when an anterior subluxation and a subsequent reduction in the tibial plateau from the femoral condyle(TRA; °), were extracted from the kinematics data recorded by both system. The verification of the MCICS was analyzed using the interclass correlation coefficient (ICC) for those values between both system. A p-value less than 0.05 were considered to be statistically significant. The pivot-shift phenomenon in all patients was determined as a sudden tibial external rotational movements in both system (Figure 1 and 2). The averaged SA in the MCICS and Navi was 12.5° (range; 5° to 30° ) and 11.0° (range; 4.2° to 18.4° ), respectively, showing the great consistency (ICC 0.808, p<0.001). The averaged TRA in the MCICS and Navi was 7.7° (range; 4.5° to 15° ) and 6.2° (range; 2.7° to 9.1° ), respectively, also showing the great consistency (ICC 0.840, p<0.001). These results indicate that based on the quantification of a dynamic rotatory knee laxity reproduced and evaluated by the pivot-shift test, our newly developed noninvasive system (MCICS) could be as accurate as the validated navigation system, particularly within range of knee flexion during the pivot-shift test. Our MCICS also has some advantages such as no limitation of the measurement location or an examining room, and capability of the analysis on the performance at high speed, which could be useful in diagnosis of ACL pathology and the postoperative evaluation of surgical reconstruction.

Complete Posterior Lateral Meniscal Root Lesion is Associated with High-Grade Pivot-Shift Phenomenon in Noncontact Anterior Cruciate Ligament Injuries

Complete Posterior Lateral Meniscal Root Lesion is Associated with High-Grade Pivot-Shift Phenomenon in Noncontact Anterior Cruciate Ligament Injuries

CORR Insights®: What Is the Mid-term Failure Rate of Revision ACL Reconstruction? A Systematic Review.

CORR Insights®: What Is the Mid-term Failure Rate of Revision ACL Reconstruction? A Systematic Review.

Primary Anterolateral Ligament Rupture in Patients Requiring Revision Anterior Cruciate Ligament Reconstruction: A Retrospective Magnetic Resonance Imaging Review

Objectives:After anterior cruciate ligament reconstruction (ACLR), only 60% of patients are able to return to their pre-injury level of sports with nearly 15% experiencing persistent rotatory instability. Young patients returning to pivoting sports experience high rates of graft tear and subsequent need for revision ACLR. Recently, the anterolateral ligament (ALL) has gained attention as an important rotatory stabilizer about the knee in prevention of the pivot shift phenomenon. It is theorized that an ALL tear at initial injury may predispose a patient to failure of primary ACLR due to persistent rotatory instability from a torn ALL. The purpose of this study was to investigate the incidence of primary ALL rupture on magnetic resonance imaging (MRI) in a population that required revision ACLR compared to a matched cohort of patients that did not require revision ACLR.Methods:Using CPT and ICD-9 and 10 codes, a retrospective search was performed within our electronic medical record database for patients who underwent ACLR and revision ACLR. Patients were excluded for a chronic ACL injury greater than 6 months, MRI obtained more than 3 months after initial injury, inability to obtain initial injury MRI, or presence of a multiligament knee injury. Age, sex, and graft type were recorded for every revision ACLR patient, and each revision patient was paired with a matched control that did not require revision ACLR. Two clinically blinded, fellowship trained musculoskeletal radiologists reviewed initial injury MRI scans to assess the integrity of the ALL. Each MRI was given a diagnosis of either an intact ALL, a partially torn ALL, or a completely torn ALL (Figure 1). The incidence of primary ALL rupture between the revision ACLR group and control ACLR group was evaluated for statistical difference using the Pearson Chi Square test.Results:1967 patients underwent ACLR at our institution between 2009-2015, and 128 patients required revision ACLR. Initial injury knee MRI was available for 55 revision ACLR patients, and 39 of these patients met inclusion criteria. For the revision cohort, the average age at primary ACLR was 21.1 years (range 13-47 years) (Table 1). Time between primary and revision ACLR was an average of 2.2 years (0.23-8.72 years). In the ACLR control cohort, the average age of ACLR was 20.9 years (range 13-47). Average length of follow-up was 0.6 years (0.21-2.8 years). The revision cohort had 17 patients with an intact ALL, 14 patients with a partial ALL tear, and 8 patients with a ALL tear on initial injury MRI. The control cohort had 18 patients with an intact ALL, 13 patients with a partial ALL tear, and 8 patients with a ALL tear. There was no statistically significant difference between the two cohorts in the incidence of primary ALL rupture (Pearson Chi-Square=0.066, p-value=0.968) (Table 1).Conclusion:The incidence of primary ALL rupture in patients undergoing revision ACLR was similar to an age and graft matched control cohort that did not require revision ACLR. These findings suggest that a primary ALL tear may not be a risk factor for subsequent ACL graft failure. It is unknown if this could be explained by an ability of the ALL to heal without intervention or if other risk factors are more important in predicting revision ACLR. Further research is needed to better understand the role of the ALL in both primary and revision ACLR.Table 1.Demographic data and ALL diagnosis for revisions and control ACLR cohorts Revision Cohort Control Cohort Total Total Patients 39 39 78 Gender (M:F)17:2217:22N/A Age at 1° ACLR, Mean (Range) 21.1 yrs (13-47) 20.9 yrs (13-47) N/A 1° Graft Type, n(%) HS Autograft25 (64.1%)26 (66.7%)51 (65.4%) BPTP Autograft13 (33.3%)13 (33.3%)26 (33.3%) HS Autograft + Allograft1 (2.6%)0 (0%)1 (1.3%) Time to Revision, Mean (Range) 2.2 yrs (0.23-8.1) N/A ALL Diagnosis (patients) Intact171835 Partially Tom141327 Completely Tom8816 Pearson Chi Square = 0.066, p-value = 0.968 ACLR=anterior cruciate ligament reconstructions, HS=hamstring, BPTB=bone patellar tendon bone, ALL=anterolateralligament

Anterolateral ligament abnormality in acute anterior cruciate ligament injuries a magnetic resonance imaging assessment on patients with high-grade pivot-shift phenomenon

Anterolateral ligament abnormality in acute anterior cruciate ligament injuries a magnetic resonance imaging assessment on patients with high-grade pivot-shift phenomenon

Complete posterolateral meniscal root tear is associated with high-grade pivot-shift phenomenon in noncontact anterior cruciate ligament injuries.

The purpose of this study was to investigate whether the complete posterolateral meniscal root tear (PLMRT) would be associated with high-grade pivot-shift phenomenon in noncontact anterior cruciate ligament (ACL) injuries. From 2013 to 2015, a total of 1095 consecutive patients were diagnosed as having noncontact ACL injuries and underwent primary ACL reconstructions. Among them, 140 patients were arthroscopically verified to have concomitant PLMRTs. Application of the exclusion criteria finally left 74 patients who were finally allocated into high-grade pivot-shift (grades II and III) group (n = 51) and low-grade pivot-shift (grades 0 and I) group (n = 23) according to the results of pre-operative pivot-shift tests performed under anesthesia. Predictors of high-grade pivot-shift phenomenon, including degree of PLMRTs, integrity of posterior MFLs, status of lateral meniscal extrusion, age, sex, body mass index (BMI), and KT-1000 arthrometer side-to-side difference (SSD), were assessed by multivariable logistic regression analysis. The proportion of patients with complete PLMRT in high-grade pivot-shift group was significantly larger than that in low-grade pivot-shift group. In addition, complete PLMRT was significantly [odds ratio (OR) 4.044; 95% CI 1.125-14.534; P = 0.032] associated with high-grade pivot-shift phenomenon in noncontact ACL injury, especially for those with a time from injury to surgery of ≥12 weeks (OR 16.593; 95% CI 1.073-56.695; P = 0.014). However, no significant association was identified between neither the integrity of posterior MFLs nor the status of lateral meniscal extrusion and the high-grade pivot-shift phenomenon. Complete PLMRT is identified to be an independent risk factor of high-grade pivot-shift phenomenon in noncontact ACL injuries, particularly for those with a time from injury to surgery of ≥12weeks. IV.

Patients with high-grade pivot-shift phenomenon are associated with higher prevalence of anterolateral ligament injury after acute anterior cruciate ligament injuries.

To compare the prevalence of concomitant anterolateral ligament (ALL) injury between patients with high-grade (grades II and III) pivot-shift and those with low-grade (grades 0 and I) pivot-shift phenomenon after acute anterior cruciate ligament (ACL) injuries. Sixty-eight patients with an acute ACL injury who showed high-grade (grades II and III) pivot-shift phenomenon were enrolled as the study group. They were matched in a 1:1 fashion to another 68 ACL-injured control participants who showed low-grade (grades 0 and I) pivot-shift phenomenon during the same study period. Patients were matched by age, sex, and time from injury to surgery. A standardized pivot-shift test was performed under anesthesia for all the patients. Two blinded musculoskeletal radiologists reviewed the magnetic resonance imaging (MRI) scans for the presence of concomitant ALL injury. The grade of an ALL injury was divided into grade 0 (normal), grade I (sprain), grade II (partial tear), and grade III (complete tear). The prevalence and the grade of concomitant ALL injury were further compared between the study group and the control group. Overall, the prevalence of concomitant ALL injury in the study group (94.1%, 64/68) was significantly higher than that in the control group [60.3%, (41/68), P < 0.05]. Specifically, there were 49 patients (49/64, 76.6%) who showed grade II/III (partial/complete tear) MRI evidence of concomitant ALL injury, which was also significantly higher than that in the control group (12/41, 29.3%). Patients with high-grade pivot-shift phenomenon showed higher prevalence of concomitant ALL injury compared to those with low-grade pivot-shift phenomenon after acute ACL injuries. Careful assessment and proper treatment of this concomitant injury should be considered especially in knees with high-grade pivot-shift phenomenon. III.

Biomechanical Role of Lateral Structures in Controlling Anterolateral Rotatory Laxity: The Iliotibial Tract

Recent research, focusing on rotatory knee laxity, has intrigued the whole orthopaedic knee community. First popularized by Hughston et al, peripheral knee injuries at the time of cruciate ligament rupture have regained more and more recognition, which has led to a better understanding of these injuries. Recent research has been focused on anterolateral rotatory instability, especially regarding those structures that are responsible for the high-grade anterior subluxation of the lateral tibial plateau when damaged. Work at Imperial College London showed that the iliotibial tract (ITT) was the primary restraint to internal tibial rotation, especially the capsulo-osseous layer of the ITT, which contributed almost 25% of controlling a 5-Nm internal rotation torque at early flexion angles. However, due to the complex fiber arrangement, the functional anatomy of the ITT is difficult to understand. Thus, this article focuses on the involvement of the internal tibial rotation in restraining internal rotation and the pivot-shift phenomenon.

The influence of applied internal and external rotation on the pivot shift phenomenon

The pivot shift test is performed in different techniques and the rotation of the tibia seems to have a significant impact on the amount of the pivot shift phenomenon. It has been hypothesised that external rotation will increase the phenomenon due to less tension at the iliotibial band in knee extension. Twenty-four patients with unilateral anterior cruciate ligament insufficiency were included prospectively. The pivot shift test was performed bilaterally in internal and external tibial rotation under general anaesthesia. Knee motion was captured using a femoral and a tibial inertial sensor. The difference between positive and negative peak values in Euclidean norm of acceleration was calculated to evaluate the amount of the pivot shift phenomenon. The pivot shift phenomenon was significantly increased in patients with ACL insufficiency when the test was performed in external [mean 5.2ms- 2 (95% CI 4.3-6.0)] compared to internal tibial rotation [mean 4.4ms- 2 (95% CI 3.5-5.4)] (p = 0.002). In healthy, contralateral knees did not show any difference between external [mean 4.0ms- 2 (95% CI 3.3-4.7)] and internal tibial rotation [mean 4.0ms- 2 (95% CI 3.4-4.6)] (ns). The pivot shift phenomenon was increased with external rotation in ACL-insufficient knees, and therefore, one should perform the pivot shift test, rather, in external rotation to easily evoke the, sometimes difficult to detect, pivot shift phenomenon. I (diagnostic study).

Is an Anterolateral Ligament Reconstruction Required in ACL-Reconstructed Knees With Associated Injury to the Anterolateral Structures? A Robotic Analysis of Rotational Knee Stability

Background: The effect of an anterolateral ligament (ALL) reconstruction on rotational knee stability and corresponding anterior cruciate ligament (ACL) graft forces using multiple knee loading conditions including the pivot-shift phenomenon has not been determined. Purpose: First, to determine the rotational stability and ACL graft forces provided by an anatomic bone–patellar tendon–bone ACL reconstruction in the ACL-deficient knee alone and with an associated ALL/iliotibial band (ITB) injury. Second, to determine the added rotational stabilizing effect and reduction in ACL graft forces provided by an ALL reconstruction. Study Design: Controlled laboratory study. Methods: A 6 degrees of freedom robotic simulator was used to test 7 fresh-frozen cadaveric specimens during 5 testing conditions: intact, ACL-sectioned, ACL-reconstructed, ALL/ITB-sectioned, and ALL-reconstructed. Lateral and medial tibiofemoral compartment translations and internal tibial rotations were measured under Lachman test conditions, 5-N·m internal rotation, and 2 pivot-shift simulations. Statistical equivalence within 2 mm and 2° was defined as P < .05. Results: Single-graft ACL reconstruction restored central tibial translation under Lachman testing and internal rotation under 5-N·m internal rotation torque (P < .05). A modest increase in internal rotation under 5-N·m internal rotation torque occurred after ALL/ITB sectioning of 5.1° (95% CI, 3.6° to 6.7°) and 6.7° (95% CI, 4.3° to 9.1°) at 60° and 90° of flexion, respectively (P = .99). Lateral compartment translation increases in the pivot-shift tests were <2 mm. ALL reconstruction restored internal rotation within 0.5° (95% CI, –1.9° to 2.9°) and 0.7° (95% CI, –2.0° to 3.4°) of the ACL-reconstructed state at 60° and 90° of flexion, respectively (P < .05). The ALL procedure reduced ACL graft forces, at most, 75 N in the pivot-shift tests and 81 N in the internal rotation tests. Conclusion: Although the ALL reconstruction corrected the small abnormal changes in the internal rotation limit at high flexion angles, the procedure had no effect in limiting tibiofemoral compartment translations in the pivot-shift test and produced only modest decreases in ACL graft forces. Accordingly, the recommendation to perform an ALL reconstruction to correct pivot-shift abnormalities is questioned. Clinical Relevance: The small changes in rotational stability after ALL/ITB sectioning would not seem to warrant the routine addition of an ALL reconstruction in primary ACL injuries. Clinical exceptions may exist, as in grossly unstable grade 3 pivot-shift knees and revision knees. However, the concern exists of overconstraining normal tibial rotations.

Anatomic dissection of the anterolateral ligament (ALL) in paired fresh-frozen cadaveric knee joints.

Different dissection studies as well as comparative studies about the anterolateral ligament of the knee (ALL) already exist and the structure's topology and properties have been shown. However, most of the studies investigating the ligament were performed in embalmed knees, which is thought to change the structural integrity of ligaments and thus the topologic and dynamic measurements. Since the biomechanical function of the ALL is not fully understood until today and a correlation with the pivot shift phenomenon is yet speculative, further studies will have to clarify its definitive importance. Its function as a limiter of internal rotation and lateral meniscal extrusion leads to the assumption of a secondary knee stabilizer. Twenty paired fresh-frozen cadaveric knees of ten donors have been dissected in a layerwise fashion. After identification of the ALL, topologic measurements were undertaken using a digital caliper. The ALL could be identified as a tender, pearly structure in front of the anterolateral joint capsule in only 60% of the dissected knee joints. Only 20% of donors had a bilateral ALL while 80% had an ALL only in one side. Mean length, thickness and width as well as topographic measurements were comparable to other available studies investigating fresh-frozen cadavers. Anatomy and topography of the ALL seem to be highly variable, but consistent within certain borders. Prevalence has to be argued though as it strongly differs between studies. The impact of an ALL absence, even if only unilateral, needs to be investigated in clinical and imaging studies to finally clarify its importance.

Prevalence and Classification of Injuries of Anterolateral Complex in Acute Anterior Cruciate Ligament Tears

To report on the prevalence of injuries of the lateral compartment occurring in cases of apparently isolated acute anterior cruciate ligament (ACL) tears and to present a classification system of anterolateral complex injuries based on the data obtained. Sixty patients operated on for an acute apparently isolated ACL tear, revealed by clinical examination and confirmed by magnetic resonance imaging, were prospectively selected. The lateral compartment was exposed and injuries were detected. Based on the data obtained, lesions of the anterolateral complex were classified as follows: Type I: multilevel rupture with individual layers torn at different levels with macroscopic hemorrhage involving the area of the anterolateral ligament (ALL) and extended to the anterolateral capsule. Type II: multilevel rupture with individual layers torn at different levels with macroscopic hemorrhage extended from the area of the ALL and capsule to the posterolateral capsule. Type III: complete transverse tear involving the area of the ALL near its insertion to the lateral tibial plateau, distal to the lateral meniscus. Type IV: bony avulsion (Segond fracture). The pivot-shift test was repeated intraoperatively after repair of lateral tears before the ACL reconstruction. Although magnetic resonance imaging was able to detect only bony injuries (Segond fracture), macroscopic tears of the lateral capsule were clearly identified at surgery in 54 of 60 patients and classified as follows: Type I: 19/60 Type II: 16/60 Type III: 13/60 Type IV: 6/60 In all cases, repair resulted in a marked reduction or apparent disappearance of the pivot-shift phenomenon. Statistical analysis showed a positive correlation between lesions of the lateral compartment, regardless of the type described, and a pivot shift graded 2 or3. Because injuries of secondary restraints often occur in cases of acute ACL tears, recognition and repair of such lesions could be considered to help ACL reconstruction to better control rotational stability. Level IV, therapeutic case series.

Quantification of the pivot-shift test using a navigation system with non-invasive surface markers.

The purpose of this study was to validate the quantitation of the pivot-shift phenomenon by using a navigation system with non-invasive surface markers. Measurements obtained using this system were compared with those obtained using commercial pin-fixed markers. Seventy patients with anterior cruciate ligament (ACL) injuries were assessed under general anaesthesia. Knee kinematics during the pivot-shift test were recorded using an image-free navigation system with a commercial transmitter placed on the thigh and lower leg (surface markers) or those fixed to the femur and the tibia via metal pin fixators (pin-fixed markers). For quantitation of the pivot-shift phenomenon, posterior tibial reduction (PTR) was calculated using the two types of navigation system markers and were then compared. PTRs measured using the two types of markers were also compared with clinical grade of the pivot-shift test, as determined by an examiner. The pivot-shift phenomenon could be identified in all patients on the navigation screen. The PTR measured using surface markers moderately correlated with that measured using pin-fixed markers (ρ=0.524, p<0.001). There were also moderate correlations between clinical grades and the PTRs measured using either the surface markers (ρ=0.522, p<0.001) or the pin-fixed markers (ρ=0.645, p<0.001). The present study demonstrated that PTR, during the pivot-shift test, may be quantified in ACL-injured knees, using a navigation system with surface markers, and that the PTR measured with surface markers moderately correlated both with the PTR obtained using pin-fixed markers and with the clinical grade of the pivot-shift test. A customised method of fixing transmitters with reflective markers to patients' thighs and shins with Velcro straps is non-invasive and could assess and record the knee kinematics, especially the pivot-shift test, in ACL-injured and ACL-reconstructed knees before, during, and after surgery using a navigation system. Case series, Level IV.

Dynamic Evaluation of Pivot-Shift Phenomenon in Double-Bundle Anterior Cruciate Ligament Reconstruction Using Triaxial Accelerometer

To evaluate the effect of initial graft tension on rotational stability and to determine the minimum required tension (MRT) based on the pivot-shift phenomenon in isolated anteromedial bundle (AMB), isolated posteromedial bundle (PLB), and double-bundle anterior cruciate ligament (ACL) reconstructions using a triaxial accelerometer during surgery. Primary double-bundle ACL reconstructions were included. The pivot-shift test and N-test were performed before and during surgery with the acceleration measurements using a triaxial accelerometer. The pivot-shift test was also manually graded. The AMB and PLB were fixed to a graft tensioning system during surgery with the following settings: (1) AMB only (AMB), (2) PLB only (PLB), and (3) AMB and PLB (A+P). The total graft tension was first set at 20N and then was increased in increments of 10N until the pivot-shift test became negative, which was defined as the MRT in each setting. Twenty-five patients were evaluated. The MRT in the AMB setting averaged 26N (range, 20 to 40N); in the PLB setting, 28N (range, 20 to 40N); and in the A+P setting, 24N (range, 20 to 40N). The MRT in the A+P setting was significantly smaller than that in the PLB setting (P= .008). The acceleration in the A+P setting was significantly smaller than that in the AMB and PLB settings both in the pivot-shift test (vs AMB: P= .007, vs PLB: P=.011) and in the N-test (vs AMB: P < .001, vs PLB: P < .001). Double-bundle ACL reconstruction better controlled rotational stability with smaller MRT than isolated PLB reconstruction at the time of surgery. In double-bundle reconstruction, the MRT based on the pivot-shift phenomenon could be larger than previously reported MRT based on anteroposterior laxity. Level IV, therapeutic case series.

The anterolateral ligament (ALL) and its role in rotational extra-articular stability of the knee joint: a review of anatomy and surgical concepts.

The anterolateral ligament of the knee (ALL) has caused a lot of rumors in orthopaedics these days. The structure that was first described by Segond back in 1879 has experienced a long history of anatomic descriptions and speculations until its rediscovery by Claes in 2013. Its biomechanical properties and function have been examined recently, but are not yet fully understood. While the structure seems to act as a limiter of internal rotation and lateral meniscal extrusion its possible proprioceptive effect remains questionable. Its contribution to the pivot shift phenomenon has been uncovered in parts, therefore it has been recognized that a concomitant anterolateral stabilization together with ACL reconstruction may aid in prevention of postoperative instability after severe ligamentous knee damages. However, there are a lot of different methods to perform this procedure and the clinical outcome has yet to be examined. This concise review will give an overview on the present literature to outline the long history of the ALL under its different names, its anatomic variances and topography as well as on histologic examinations, imaging modalities, arthroscopic aspects and methods for a possible anterolateral stabilization of the knee joint.