Ligament Deficiency Research Articles

Identification of Kinetic Abnormalities in Male Patients after Anterior Cruciate Ligament Deficiency Combined with Meniscal Injury: A Musculoskeletal Model Study of Lower Limbs during Jogging.

There is little known about kinetic changes in anterior cruciate ligament deficiency (ACLD) combined with meniscal tears during jogging. Therefore, 29 male patients with injured ACLs and 15 healthy male volunteers were recruited for this study to investigate kinetic abnormalities in male patients after ACL deficiency combined with a meniscal injury during jogging. Based on experimental data measured by an optical tracking system, a subject-specific musculoskeletal model was employed to estimate the tibiofemoral joint kinetics during jogging. Between-limb and interpatient differences were compared by the analysis of variance. The results showed that decreased knee joint forces and moments of both legs in ACLD patients were detected during the stance phase compared to the control group. Meanwhile, compared with ACLD knees, significantly fewer contact forces and flexion moments in ACLD combined with lateral and medial meniscal injury groups were found at the mid-stance, and ACLD with medial meniscal injury group showed a lower axial moment in the loading response (p < 0.05). In conclusion, ACLD knees exhibit reduced tibiofemoral joint forces and moments during jogging when compared with control knees. A combination of meniscus injuries in the ACLD-affected side exhibited abnormal kinetic alterations at the loading response and mid-stance phase.

Comparison of the in-vivo kinematics of three different knee prosthesis designs during a step-up movement

BackgroundThere is no consensus on the importance of the kinematics of the prosthetic joint for the clinical outcome after total knee arthroplasty. A 3-armed randomized controlled trial was done to determine and compare the in vivo kinematics of a posterior cruciate-retaining and two posterior cruciate-sacrificing (Anterior-Stabilized and Posterior-Stabilized) prosthetic designs from the same total knee arthroplasty system. Since the anterior-stabilized and posterior-stabilized designs are posterior cruciate ligament-sacrificing designs, we hypothesized they would have similar contact-point kinematics. Further, we hypothesized that the cruciate-retaining design would have contact-point kinematics different from the anterior-stabilized and the posterior-stabilized designs, but comparable to a native knee. MethodsThirty-nine patients with a well-functioning total knee arthroplasty one year postoperatively underwent kinematic analysis of a weight-bearing step-up movement under fluoroscopic recording. Model-based radiostereometric analysis was used to determine anteroposterior contact-point translations and rotations through the movement path to assess knee kinematics. FindingsThe cruciate-retaining and anterior-stabilized groups' medial and lateral contact-points displayed similar paradoxical posterior translations during step-up in the magnitude of 7 and 2 mm, respectively. In contrast, the posterior-stabilized group's contact-points translated anteriorly by 4 and 10 mm throughout the movement and were significantly more posterior than the cruciate-retaining and the anterior-stabilized groups from >100° to 40° of flexion. The femur rotated internally with all designs. InterpretationThe cruciate-retaining and anterior-stabilized designs displayed similar contact-point translation patterns during a step-up movement. Only the posterior-stabilized design showed a pattern comparable to native knees. Conversion from a cruciate-retaining to an anterior-stabilized design because of posterior cruciate ligament insufficiency will not change knee kinematics.

A combined anterior cruciate ligament/Meniscal injury alters the patellofemoral joint kinematics of anterior cruciate ligament-deficient knees during a single-leg lunge exercise: A cross-sectional study.

Anterior cruciate ligament deficiency (ACLD) is often accompanied by concomitant meniscal tears. The study aimed to assess the kinematic alterations of patellofemoral joint (PFJ) in anterior cruciate ligament deficiency knees with or without meniscal tears during a single-leg lunge. Sixty unilateral anterior cruciate ligament deficiency patients were recruited for the study, including 15 isolated anterior cruciate ligament deficiency patients (group 1), 15 anterior cruciate ligament deficiency patients with medial meniscal tears (group 2), 15 patients with lateral meniscal tears (group 3) and 15 patients with combined medial/lateral meniscal tears (group 4). The patellofemoral joint kinematics were determined by a single fluoroscopic image system. Patellofemoral joint kinematics of contralateral anterior cruciate ligament-intact (ACLI) and anterior cruciate ligament deficiency knees were compared. With or without meniscal tears, anterior cruciate ligament deficiency knees had significantly smaller patellar flexion than the anterior cruciate ligament-intact knees (∼5°-10°; p < 0.05). anterior cruciate ligament deficiency knees had more patellar lateral tilting by approximately 1°-2° than the anterior cruciate ligament-intact knees (p < 0.05) in groups 2, 3, and 4. anterior cruciate ligament deficiency groups with medial meniscal deficiencies showed consistent increased lateral patellar translations (2-4mm) compared to the anterior cruciate ligament-intact group during a single-leg lunge. The results indicate that meniscal tears alter anterior cruciate ligament deficiency patients' patellofemoral joint kinematics and the types of the meniscal injuries also affect the patellofemoral joint kinematics. Considering the varying effects of meniscal tears on the patellofemoral joint kinematics, specific treatments for anterior cruciate ligament deficiency patients with meniscal tears should be proposed in some closed kinetic chain (CKC) exercise programs, such as single-leg lunge.

How Does Anterior Cruciate Ligament Incompetence Influence the Varus Osteoarthritic Knee?

Introduction: The aims of our study were: (i) to assess the correlation of anterior cruciate ligament (ACL) deficiency with severity of preoperative varus deformity in osteoarthritic knees, (ii) to compare posterior medial femoral condyle (MFC) changes in ACL deficient vs ACL competent knees, and (iii) to compare the mean femoral external rotation of ACL deficient vs ACL competent knees. Methods: 250 consecutive ACL deficient and ACL competent patients each, undergoing total knee arthroplasty (TKA) for osteoarthritis with a varus deformity were reviewed retrospectively. Data from a prospectively collected computer navigation assisted TKA database was analyzed for an association between ACL insufficiency and: severity of the varus deformity, incidence of posterior MFC compensatory changes, and the magnitude of femoral component external rotation. Results: A statistically significant positive correlation was found between ACL incompetence and- (1) Severity of the knee varus deformity (p < 0.001), (2) Incidence of compensatory posterior MFC hypertrophy (p < 0.001) and (3) Femoral component external rotation required to balance the knee in flexion during TKA (p < 0.001). Conclusion: ACL deficiency is associated with an increase in the severity of the varus deformity. A significantly higher incidence of posterior MFC hypertrophy and increased values of the combined Whiteside-PCA angle are noted in ACL deficient knees compared with knees with an intact ACL. Multiple intraoperative landmarks must be assessed for setting femoral component rotation while performing TKA in the ACL deficient knee.

Efficient Subject-Independent Detection of Anterior Cruciate Ligament Deficiency Based on Marine Predator Algorithm and Support Vector Machine.

Anterior cruciate ligament (ACL) deficiency not only reduces knee stability, but also increases the risk of more disease and impairs daily life, thus requiring efficient detection of ACL deficiency. To build an efficient subject-independent ACL deficiency detection model, this study proposes a new method called SVM-MPA that fuses marine predator algorithm (MPA) and support vector machine (SVM) for simultaneous feature selection, hyperparameter optimization and classification. 35ACL-deficient (ACLD) and 35 ACL-intact (ACLI) participants were recruited to collect 6-degree-of-freedom knee kinematic data. Then, 216-dimensional multi-domain features covering time domain, frequency domain, time-frequency domain and nonlinearity were extracted. The error rate of SVM classification based on 5-fold cross-validation was used to construct the fitness of MPA, and MPA served to select features and optimize two hyperparameters for SVM. The majority voting strategy-based post-processing was introduced to convert the gait cycle-level to knee-level ACL deficiency detection. Comparing with 7 well-known meta-heuristic algorithms and running all 20 times, the best average gait cycle-level ACL deficiency detection performance (sensitivity: 96.78±0.4.84%, specificity: 99.43±5.70%, and accuracy: 98.48±1.70%) was obtained using the proposed method. With post-processing, this study improved the best (final) detection performance (sensitivity: 97.78±4.97%, specificity: 100±0.00%, and accuracy: 99.13±1.94%). These results demonstrate the feasibility and effectiveness of the proposed method and shows that an efficient subject-independent ACL deficiency detection model can be constructed using the proposed method, which makes it possible to provide a non-invasive, objective and accurate preoperative auxiliary detection method for diagnosing ACL deficiency clinically.

The Relationship of Knee-related Quality of Life With Function, Psychological Factors, Strength, Performance, and Postural Stability After ACL Reconstruction: A Cross-Sectional Study.

Patients after anterior cruciate ligament reconstruction (ACLR) have decreased health-related quality of life (QoL) compared with healthy control participants. Few studies have verified the predictors of QoL using Quality of Life Outcome Measure Questionnaire for Chronic Anterior Cruciate Ligament Deficiency (ACL-QoL), and no study has verified the relationship of psychological factors and knee function with ACL-QoL in patients after ACLR. Knee functional status, muscle strength, performance in hop tests, postural stability, and psychological factors would be the predictors of QoL after ACLR. Cross-sectional study. Level 4. A total of 131 participants who had undergone ACLR at least 6 months previously were evaluated. QoL was assessed using ACL-QoL; knee functional status, using International Knee Documentation Committee Subjective Knee (IKDC) and global rating scale (GRS); psychological readiness, using Anterior Cruciate Ligament Return to Sport after Injury Scale (ACL-RSI); kinesiophobia, using Tampa Scale for Kinesiophobia (TSK-17); knee strength, using isokinetic dynamometer; performance, using single-leg hop tests; and postural stability, using Biodex Balance System. Pearson's linear correlation and stepwise hierarchical multiple linear regression analyses were performed to verify the predictors of QoL. ACL-QoL showed a moderate correlation with IKDC (r = 0.69), GRS (r = 0.55), ACL-RSI (r = 0.50), and TSK-17 (r = -0.49). ACL-QoL presented none to low correlations with the variables of muscle strength, postural stability, and performance in hop tests. The variables related to the knee functional status and psychological factors (IKDC, GRS, ACL-RSI, and TSK-17) were found to be the predictors of QoL (R2 = 0.56; P = 0.01). Knee functional status, psychological readiness, and kinesiophobia were the predictors of knee-related QoL in patients after ACLR. These results can assist clinicians in the therapeutic monitoring of the factors that may interfere with QoL in patients after ACLR.

Intercondylar width index of the tibia in the dogs: A morphological study

Morphological characteristics of the proximal tibia affect the orthopedic balance of the knee region. Such as the width of the condyles, tibial plateau angle, position of the patella; Intercondylar width is one of these features as well. The objectives of this study are to calculate the intercondylar width index of the tibia (ICWI) in dogs, to determine if there are gender-related differences in ICWI, and to compare the ICWI among the six breeds of dog. For these aims, the tibial bones of 84 dogs from 26 different breeds were used. The radiographs of tibias were taken, and the tibial plateau and intercondylar widths were measured. The intercondylar width index was calculated using the following formula: (intercondylar width/tibial plateau width) *100. The mean intercondylar width index of the dogs was 19.2±2.72. The index values of male and female dogs were 19.1±3.32 and 19.3±2.02, respectively. The significant differences in the index were not determined between male and female dogs, but the significant difference was determined among dogs’ breeds. The dogs in the high-risk breeds had significantly smaller eminence width index value than the dogs in the low-risk breeds related with the non-traumatic cranial cruciate ligament rupture. The results of this study suggested performing further clinical studies to evaluate whether the difference in intercondylar width index among breeds in dogs is associated with cranial cruciate ligament deficiency.

ACLD patients exhibit additional knee kinematic asymmetries at the speed level of healthy subjects.

Anterior cruciate ligament deficiency (ACLD) patients tend to walk slowly but try to catch up with the speed level of healthy subjects daily. Exploring the effects of the walking speed level of healthy subjects on the ACLD patients’ knee kinematics is important to improving non-operative treatments and delaying the progression of posttraumatic knee osteoarthritis. This study aimed to explore whether healthy controls’ walking speed level leads to additional knee kinematic asymmetries in patients with ACLD. 27 ACLD patients and 29 healthy controls were recruited for the study. The ACLD patients walked at two levels of walking speed, including self-selected and healthy controls’ walking speed levels. A three-dimensional gait analysis system was used to collect their knee kinematic data. ACLD patients exhibited more kinematic asymmetries when walking at healthy controls’ walking speed level than at their self-selected speeds. The kinematic asymmetries included increased posterior tibial translation (4.6 mm) and anteroposterior tibial ROM (3.9 mm), abduction angle (1.5°), and distal tibial translation (3.2 mm) asymmetries (p < 0.05). Our findings are meaningful for developing non-operative treatment strategies for patients with ACLD. To get fewer knee kinematic asymmetries, self-selected walking speed could be suggested for patients with ACLD daily rather than the speed levels of healthy subjects.

Is combined robotically assisted unicompartmental knee arthroplasty and anterior cruciate ligament reconstruction a good solution for the young arthritic knee?

Anterior cruciate ligament (ACL) deficiency can be a consequence or a cause of femoro-tibial osteoarthritis (OA). Several studies have published satisfactory outcomes of unicompartimental knee arthroplasty (UKA) and combined ACL reconstruction despite its absence classically being considered a contraindication. A major challenge in the ACL deficient knee is obtaining appropriate gap balancing and limb axis. Robotically assisted UKA allows for precise control of these factors; however, it's utilisation as a tool with combined ACL reconstruction and UKA has not been described. The purpose of this study was to evaluate the clinical and radiological outcomes of robotically assisted UKA with combined ACL reconstruction. This was a retrospective single-centre study of ten patients operated by a single surgeon from 2016 to 2020. All surgery was performed using a cemented fixed bearing UKA prosthesis (Journey uni, Smith and Nephew®) (8 medial, 2 lateral) inserted with the assistance of an image-free robotic-assisted system (BlueBelt, Navio, Smith and Nephew®). All ACL reconstructions were performed using hamstring autograft. Clinical assessment included International Knee Score (IKS) score, Tegner score and patient satisfaction. Radiological assessment was performed to assess radiolucent lines, progression of OA in the other compartments, Hip-Knee-Ankle angle and Posterior Tibial Slope. There were eight females (80%), mean age was 57 ± 7 [48-70], mean BMI was 26 ± 3 [22-31]. The mean follow-up was 45months ± 13months [24-66]. Mean post-operative IKS knee and function score were respectively 96 ± 4.5 [88-100] and 93 ± 8.2 [74-100], mean Tegner score was 4.5 ± 1.4 [3-6]. Nine patients (90%) returned to sport; one patient (10%) was dissatisfied because of residual pain preventing a return to a desired level of sport. 100% of the radiological objectives were achieved. No radiolucent lines were seen at the last follow-up. There were two re-operations (20%) for stiffness requiring arthroscopic arthrolysis at two and threemonths respectively following surgery, with full recovery of the flexion at the last follow-up in both cases. No other complications were observed. Robotic UKA associated with ACL reconstruction provides satisfactory early patient outcomes and accurate implant positioning. The first results in terms of return to sports were promising.

Is there any benefit in the combined ligament reconstruction with osteotomy compared to ligament reconstruction or osteotomy alone?: Comparative outcome analysis according to the degree of medial compartment osteoarthritis with anterior or posterior cruciate ligament insufficiency.

The purpose of this study was to compare the outcomes of middle-aged patients with anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) insufficiency by assessing different groups: high tibial osteotomy (HTO), HTO with combined ligament reconstruction, and isolated ligament reconstruction according to the alignment change and medial compartment osteoarthritis (OA). From 2014 to 2019, middle-aged (40-65years) patients with knee instability were enrolled in this retrospective study. They were categorized into three groups: group I, HTO; group II, HTO with combined ACL or PCL reconstruction; and group III, isolated ligament reconstruction. Radiological outcomes, including Kellgren-Lawrence grade, mechanical femorotibial angle (mFTA), weight-bearing line (WBL) ratio, and posterior tibial slope were compared. Knee stability and clinical outcomes were also compared. Seventy-nine patients completed the final assessment. Group I was older than other two groups (p = 0.006). Groups I and II had a higher body mass index (p = 0.043) and more preoperative varus alignment than group III (p < 0.001). OA severity was ranked in the order of group I, II, and III (p < 0.001). Group I showed more valgus alignment than group II after HTO (p = 0.024 for mFTA and 0.044 for WBL ratio, respectively). Compared to their preoperative status, all three groups showed significant improvement in knee stability (p < 0.001); however, group I showed inferior knee stability regardless of ACL or PCL reconstruction (p < 0.001 and 0.043, respectively). All clinical scores significantly improved in the three groups (p < 0.001), and they showed comparable clinical outcomes in the final assessment. Our strategy in managing middle-aged patients with knee instability according to the varus alignment and medial degeneration showed favorable stability and clinical outcomes. Middle-aged patients with knee instability should be managed with different strategies depending on their status. Case-control study; Level-III.

Varus stress MRI in the refined assessment of the posterolateral corner of the knee joint

Magnetic resonance imaging (MRI) is commonly used to assess traumatic and non-traumatic conditions of the knee. Due to its complex and variable anatomy, the posterolateral corner (PLC)—often referred to as the joint’s dark side—remains diagnostically challenging. We aimed to render the diagnostic evaluation of the PLC more functional by combining MRI, varus loading, and image post-processing in a model of graded PLC injury that used sequential transections of the lateral collateral ligament, popliteus tendon, popliteofibular ligament, and anterior cruciate ligament. Ten human cadaveric knee joint specimens underwent imaging in each condition as above, and both unloaded and loaded using an MR-compatible device that standardized loading (of 147 N) and position (at 30° flexion). Following manual segmentation, 3D joint models were used to computationally measure lateral joint space opening for each specimen, configuration, and condition, while manual measurements provided the reference standard. With more extensive ligament deficiency and loading, lateral joint spaces increased significantly. In conclusion, varus stress MRI allows comprehensive PLC evaluation concerning structural integrity and associated functional capacity. Beyond providing normative values of lateral compartment opening, this study has potential implications for diagnostic and surgical decision-making and treatment monitoring in PLC injuries.

Primary TKA in patients with major deformities and ligament laxities: promising results of an intermediate constrained implant at mid-term follow-up.

Total knee arthroplasty (TKA) in major deformities with ligament insufficiency may require a higher constraint, with bone sacrifice and concerns about long-term survivorship. Mid-level constraint liners have been recently introduced, but few studies described their outcomes. The aim of this study is to evaluate the short to mid-term outcomes of a constrained postero-stabilized (CPS) insert for primary TKA in moderate to severe deformities. All patients who underwent TKA using a CPS liner in two centers between 2015 and 2017 were included in the study. The indications were: (1) valgus deformity type 2-3 partially correctable; (2) severe varus deformity with varus thrust; (3) post-traumatic deformity with major ligamentous insufficiency and any case of intra-operative ligament insufficiency. Patients were evaluated according to the Knee Society Scoring System (KSS), the Hospital for Special Surgeryscore (HSS), the Western Ontario and Mc Master University (WOMAC) and the Oxford Knee score (OKS). X-rays were evaluated according to the Knee Society Roentgenographic Evaluation System. Forty-seven TKA were included, with an average age of 66.1 ± 10.3years and an average follow-up of 68.4 ± 6months. All patients demonstrated a moderate to severe pre-operative mediolateral instability. All the scores significantly improved (p < 0.0001). In 71.4% of cases, the outcomes were excellent or very good. There were no failures due to aseptic loosening but one failure due to a traumatic ligament rupture. The cumulative survivorship was 97.9% ± 2.1% at 84months. This mid-range constraint total knee replacement demonstrated promising outcomes and survival at mid-term follow-up. IV (case series).

Computational analysis of tibial slope adjustment with fixed-bearing medial unicompartmental knee arthroplasty in ACL- and PCL-deficient models.

AimsA functional anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) has been assumed to be required for patients undergoing unicompartmental knee arthroplasty (UKA). However, this assumption has not been thoroughly tested. Therefore, this study aimed to assess the biomechanical effects exerted by cruciate ligament-deficient knees with medial UKAs regarding different posterior tibial slopes.MethodsACL- or PCL-deficient models with posterior tibial slopes of 1°, 3°, 5°, 7°, and 9° were developed and compared to intact models. The kinematics and contact stresses on the tibiofemoral joint were evaluated under gait cycle loading conditions.ResultsAnterior translation increased in ACL-deficient UKA cases compared with intact models. In contrast, posterior translation increased in PCL-deficient UKA cases compared with intact models. As the posterior tibial slope increased, anterior translation of ACL-deficient UKA increased significantly in the stance phase, and posterior translation of PCL-deficient UKA increased significantly in the swing phase. Furthermore, as the posterior tibial slope increased, contact stress on the other compartment increased in cruciate ligament-deficient UKAs compared with intact UKAs.ConclusionFixed-bearing medial UKA is a viable treatment option for patients with cruciate ligament deficiency, providing a less invasive procedure and allowing patient-specific kinematics to adjust posterior tibial slope. Patient selection is important, and while AP kinematics can be compensated for by posterior tibial slope adjustment, rotational stability is a prerequisite for this approach. ACL- or PCL-deficient UKA that adjusts the posterior tibial slope might be an alternative treatment option for a skilled surgeon.Cite this article: Bone Joint Res 2022;11(7):494–502.

Congenital Anterior Cruciate Ligament Deficiency and Meniscal Tear with Fibular Hemimelia Deformities Managed By Reconstructive Procedures in Two Stages

Congenital cruciate deficiency is associated with many musculoskeletal and congenital abnormalities. Long-standing instability eventually predisposes them to meniscal tears or cartilage damage. We report a case of anterior cruciate ligament (ACL) aplasia with fibular hemimelia and a bucket handle meniscal tear successfully managed with staged procedures. The meniscal tear was repaired, and ACL reconstruction was done in the first stage and was previously published. Valgus deformity of the tibial shaft along with splaying of toes was managed at the second stage (5 months from the first stage), and follow-up result at 3 years from the first surgery is presented. Meniscal pathologies should be suspected in patients with congenital malformations, and correction of the deformity can prevent further episodes of meniscal injuries.

Comparison of incidence of medial meniscal injury in small dogs (≤15 kg) and medium-to-large dogs (>15 kg) with naturally occurring cranial cruciate ligament disease undergoing tibial plateau levelling osteotomy: 580 stifles (2015 - 2019).

To investigate whether a difference exists in incidence of medial meniscal tears between small (≤15 kg) and medium-to-large (>15 kg) dogs with naturally occurring cranial cruciate ligament disease. Records were retrospectively reviewed to identify the incidence of medial meniscal tears in dogs undergoing tibial plateau levelling osteotomy. Degree of cruciate insufficiency, method of identification (arthroscopy or arthrotomy), tibial plateau angle, weight and signalment were recorded. A two-proportion z-test with clustering adjustment was used to compare the meniscal tear rate between the two groups. Logistic regression analysis was used to investigate the effects of variables on medial meniscal tears. Seventy-six stifles in 67 small dogs and 504 stifles in 384 medium-to-large dogs were included. The rate of meniscal injury at index surgery was 38.2% in small dogs and 36.7% in medium-to-large dogs. The subsequent meniscal tear rate was 1.3% in small dogs and 8% in medium-to-large dogs. The difference in meniscal tear rate was not statistically significant at either index surgery or subsequently. Degree of cruciate ligament insufficiency and use of arthroscopy were significantly associated with medial meniscal tears at index surgery. No variables were significantly associated with subsequent medial meniscal tears. No significant difference exists in medial meniscal tear rate between small and medium-to-large dogs either at index surgery or subsequently. The index of suspicion of concurrent medial meniscal tears should be higher in dogs with complete tear of the cranial cruciate ligament but a partial tear does not preclude meniscal pathology.

The Dynamic Effect of Anterior Cruciate Ligament Deficiency on Patellar Height.

The anterior tibial translation (ATT) in case of Anterior Cruciate Ligament (ACL) tear can lead to dynamic alterations of the extensor apparatus biomechanics. The aim of this study is to evaluate the dynamic effect of isolated ACL deficiency on patellar height. The hypothesis is that the ATT of ACL-insufficient knees dynamically reduces patellar height. Skeletally mature patients who underwent ACL reconstruction using hamstring graft between January and December 2018 were included in this study.The Posterior Tibial Slope (PTS), Caton-Deschamps (CDI), modified Insall-Salvati (MISI), and Blackburne-Peel (BPI) indices were calculated in standard lateral and TELOS X-rays. The mean of the measurements calculated between two observers was used to compare these parameters. 95 patients (M: 57; F: 38; 95 knees) were included in the study with a mean age of 31.8years (16-56years old). Significant patellar height reduction (CDI: 0.11 [-0.32; 0.31]; MISI: 0.09 [-0.66; 0.30]) was reported in TELOS compared with standard lateral knee radiography (p < 0.001). 20.0% of the study knees reported an abnormal CDI and 84.2% (16/19 knees) of them reduced this index to within normal limits in TELOS. 20.0% of the knees with mild patella alta reduced CDI in TELOS but always remained above 1.2. The abnormal ATT in case of ACL-deficient knees results in a lowering effect of the patella in TELOS X-rays. In patients with ACL tear and anterior pain the reconstructive ligament surgery should be performed to avoid also chronic anterior knee pain. Basic Science Study (Case Series). The decrease in patellar height in stress-X-rays compared with standard lateral knee radiography in ACL deficient knees, should be considered as a possible contributing cause of anterior pain in these patients.

Is there a biomechanical “Rule of Thirds” after ACL injury and reconstruction?

Purpose and objectiveThe purpose of this study was to analyze the biomechanical outcomes of patients with Anterior Cruciate Ligament (ACL) deficiency or insufficiency and ACL reconstruction and to determine if they follow a biomechanical “Rule of Thirds.” Background and principle resultsThe Cincinnati Group reported nearly four decades ago that approximately one-third of patients do not experience a decline in biomechanical function in the absence of an ACL, one-third adapt their biomechanics to avoid knee symptoms, and one-third of patients do not adapt biomechanically to the loss of their ACL in order to function during activities of daily living without pain, swelling and giving way episodes. Subsequently, three decades ago the San Diego Group developed the Surgical Risk Factor (SURF) algorithm, which was designed to prospectively classify the biomechanics of patients who are ACL deficient. These classification systems have also delineated patient function into three categories. Currently, especially over the last decade, a growing body of work has documented that the incidence of second ACL injuries is consistent with the division of patient function by thirds. Approximately one-third of young, active individuals who return to high intensity sports sustain a second injury to either the ipsi- or contralateral knee. Summary and major conclusionsIn this Biomechanics focused article in the Journal of Orthopedics, the authors describe differential patient outcomes with a Rule of Thirds concept, including the original study performed by our former group in Cincinnati and the SURF algorithm out of San Diego, the authors also present second ACL injury rates and how they are consistent with the Rule of Thirds, as well as the biomechanical implications for patient care.

Biomechanical Rationale of Correction Osteotomy and Overcorrection

Lower extremity alignment is a factor paramount in the etiology across various degenerative as well as ligamentous pathologies of the knee and has been shown to be predictive for the postoperative success in a range of reconstructive procedures. Alignment corrective osteotomies have demonstrated to produce favorable outcomes by unloading the affected compartment and optimizing the biomechanical conditions for ligamentous stability, with a consensus on the optimal osteotomy type and configuration as well as targets of correction lacking to date. With valgus correction aiming for a neutral alignment, in varus correction, biomechanical as well as clinical evidence advocates an overcorrection to a valgus of 50%-65% on the tibial plateau depending on the underlying pathology. Solid evidence advocates to factor a preoperative intraarticular deformity, patellar height as well as collateral ligamentous laxity into planning and proposes a choice of tibial or/and femoral correction aligned with a slope-neutral preservation of a physiological coronal knee joint line of <4°. In the setting of a recurrent anterior cruciate ligament deficiency with a pathological posterior slope >12°, the biomechanical data support a correction via anterior closing wedge osteotomy and propose a simultaneous correction of concomitant varus malalignment depending on the state and competence of medial and (postero-)lateral structures.

Anatomy, Biomechanics, and Reconstruction of the Anterolateral Ligament of the Knee Joint.

Despite remarkable advances in the clinical outcomes after anterior cruciate ligament reconstructions (ACLRs), residual rotational instability of the knee joint remains a major concern. Since the anterolateral ligament (ALL) on the knee joint has been “rediscovered”, the role of anterolateral structures, including ALL and deep iliotibial band, as secondary stabilizers of anterolateral rotatory instability has gained interest. This interest has led to the resurgence of anterolateral procedures combined with ACLRs to restore rotational stability in patients with anterior cruciate ligament (ACL) deficiencies. However, the difference in concepts between anterolateral ligament reconstructions (ALLRs) as anatomical reconstruction and lateral extra-articular tenodesis (LETs) as non-anatomical reinforcement has been conflicting in present literature. This study aimed to review the anatomy and biomechanics of anterolateral structures, surgical techniques, and the clinical outcomes of anterolateral procedures, including LET and ALLR, in patients with ACL deficiencies.

Excellent outcomes with combined single stage Physica ZUK medial unicompartment knee replacement and anterior cruciate ligament reconstruction results in young, active patients with instability and osteoarthritis with a mean follow up of 5 years

Background (including the aim of the study)Young and more active patients with medial compartment osteoarthritis (OA) in conjunction with anterior cruciate ligament (ACL) deficiency are difficult to treat. The aim of this study was to explore the outcomes of combined fixed bearing Physica ZUK medial unicompartmental knee replacement (UKR) (Lima Corporate, Udine Italy) with ACL reconstruction for patients presenting with isolated medial compartment OA and symptomatic ACL deficiency. MethodsPatients who underwent simultaneous single stage ACL reconstruction and medial UKR between 2012 and 2020 by a single surgeon (GG) were included. Preoperative outcome measures including Lysholm, Tegner, Oxford Knee Score and VAS pain score were evaluated and were repeated postoperatively at the most recent follow up appointment. ResultsTwenty four patients underwent simultaneous combined ACL and ZUK Medial UKR with a mean follow up of 5.1 years. Significant improvements in Lysholm (p < 0.001), Tegner (p < 0.001), Oxford Knee Score (p < 0.001) and VAS pain scores (p < 0.001) were seen with this combined approach with all patients returning to sport. Two patients had a minor peri-operative complication, which was treated conservatively. There were no revision procedures, and no evidence of implant loosening, however one patient had deceased due to an unrelated illness. ConclusionUKR combined with ACL reconstruction can be an effective treatment option for selected patients suffering from medial unicompartmental knee osteoarthritis and symptomatic ACL deficiency. This allowed active patients to return to sports, addressing both instability and OA pain in a specific patient population.