Elevated Posterior Tibial Slope Is Associated With Anterior Cruciate Ligament Reconstruction Failures: A Systematic Review and Meta-Analysis

Effect of Slope-Reducing Tibial Osteotomy With Primary Anterior Cruciate Ligament Reconstruction on Clinical and Radiological Results in Patients With a Steep Posterior Tibial Slope and Excessive Anterior Tibial Subluxation: Propensity Score Matching With a Minimum 2-Year Follow-up

BACKGROUND

A steep posterior tibial slope (PTS) and excessive anterior tibial subluxation of the lateral compartment (ASLC) have been considered to be associated with inferior graft outcomes in primary anterior cruciate ligament (ACL) reconstruction (ACLR). Case series studies have demonstrated that combined slope-reducing tibial osteotomy can greatly improve knee functional scores and stability in revision ACLR. However, there is currently no comparative study evaluating the clinical benefits of osteotomy procedures in primary ACLR.

PURPOSE

To assess the feasibility of combined slope-reducing tibial osteotomy and primary ACLR in patients with a steep PTS and excessive ASLC and to explore the suitable threshold for osteotomy.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between 2016 and 2022, of the 108 patients with ACL injuries who had a steep PTS (≥15°) and a follow-up ≥2 years, 30 patients with excessive ASLC (≥6 mm) underwent concomitant slope-reducing tibial osteotomy and ACLR (osteotomy group), and 78 patients underwent isolated ACLR (control group). Propensity score matching at a 1:2 ratio was used to match preoperative variables between the 2 groups. After matching preoperative variables, 25 and 48 patients underwent combined surgery and isolated ACLR, respectively. The primary outcome was ACL graft status (failure and laxity rates). The secondary outcomes were ASLC and anterior tibial subluxation of the medial compartment (ASMC), KT-1000 arthrometer side-to-side difference (SSD), pivot-shift grade, and second-look arthroscopic findings. Stratified analysis was performed with 1° PTS increments to explore the osteotomy threshold.

RESULTS

Both groups were comparable in terms of age, sex, side, body mass index, PTS, graft diameter, time from injury to surgery, ASLC, ASMC, KT-1000 arthrometer SSD, pivot-shift grade, and meniscal injuries (all P > .05). The mean PTS significantly decreased from 18.2° to 6.7° (P < .001) in the osteotomy group. The 2-year rate of ACL graft laxity was 12.0% in the osteotomy group and 35.4% in the control group, with a statistically significant difference (P = .033). There was no significant difference in the 2-year rate of ACL graft failure between the 2 groups (8.0% vs 12.5%, respectively; P = .559). The final follow-up data showed that improvements in ASLC (4.5 vs 6.4 mm, respectively; P = .012) and ASMC (2.8 vs 4.5 mm, respectively; P = .014) were more significant in the osteotomy group compared with the control group. On the second-look arthroscopic examination, the incidence of graft roof impingement in the control group was significantly higher than that in the osteotomy group (22.9% vs 4.0%, respectively; P = .039). No significant differences were observed between the 2 groups in terms of KT-1000 arthrometer SSD and high-grade pivot shift (P > .05). Furthermore, stratified analysis revealed that the combined procedure significantly reduced the ACL graft failure rate and improved the KT-1000 arthrometer SSD in patients with a preoperative PTS ≥16°.

CONCLUSION

Slope-reducing tibial osteotomy combined with primary ACLR significantly decreased the amount of anterior tibial subluxation, the incidence of graft roof impingement, and the graft laxity rate for patients with a steep PTS (≥15°) and excessive ASLC (≥6 mm). Furthermore, in patients with a PTS ≥16°, the combined procedure improved anterior knee stability and reduced the graft failure rate. Therefore, a PTS ≥16° plus ASLC ≥6 mm may be considered an appropriate indication for combining slope-reducing tibial osteotomy with primary ACLR.

Sagittal Slope-Reducing High Tibial Osteotomy Decreases Anterior Cruciate Ligament Force and Coupled Internal Tibial Rotation Under Pivoting Loads: A Computational Modeling Study

BACKGROUND

Sagittal-plane slope-reducing high tibial osteotomy (HTO) can reduce the risk of anterior cruciate ligament (ACL) injury in knees with a high posterior tibial slope. The biomechanical effect of slope-reducing HTO on tibiofemoral kinematics and force carried by the ACL remains less well understood.

HYPOTHESIS

Decreased tibial slope will be associated with decreased ACL force, coupled internal tibial rotation (ITR), and anterior tibial translation (ATT) under both compressive and combined compressive and valgus loads.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Computational models of 10 cadaveric knees were created using magnetic resonance imaging- and computed tomography-based 3-dimensional renderings of the bones, articular cartilage, and menisci. Virtual slope-reducing HTO was performed on each tibial geometry in 1° increments, creating tibial slopes spanning -5° to 15°. All knees were flexed to 15°, and loads consisting of (1) axial compression (100 N) and (2) combined axial compression (100 N) and valgus torque (8 N·m) were then applied to each knee at each tibial slope. The outcome measures were ACL force, coupled ITR, and ATT. Relationships between tibial slope and each outcome measure were assessed via linear regression (α = .05), and the effects of 10° slope-reducing HTO, from 15° to 5°, on each outcome measure were reported.

RESULTS

A 10° slope-reducing HTO decreased ACL force by 53% under compression (1.7 N of ACL force per degree decrease in tibial slope; P < .001) and 47% under combined compression and valgus (4.7 N of ACL force per degree decrease in tibial slope; P < .001). Regarding kinematics, a 10° slope-reducing HTO decreased coupled ITR by 64% under combined compression and valgus (0.99° of coupled ITR per degree decrease in tibial slope; P < .001). Finally, a 10° slope-reducing HTO decreased ATT by 54% under compression (0.14 mm of ATT per degree decrease in tibial slope; P < .001).

CONCLUSION

Slope-reducing HTO decreased ACL force linearly by reducing ATT with compression and also by decreasing coupled ITR with combined compression and valgus.

CLINICAL RELEVANCE

Slope-reducing HTO decreased ATT and coupled ITR, dampening movements known to load the ACL. These findings may provide a further biomechanical basis for the ability of slope-reducing HTO to decrease the risk of ACL injury.

The Commonest Indication for Performing a Slope-Reducing Osteotomy With an Anterior Cruciate Ligament Reconstruction Is Graft Failure With a Posterior Tibial Slope of 12° or Greater: A Systematic Review of Indications, Techniques, and Outcomes

PURPOSE

To (1) summarize indications/inclusion criteria and contraindications/exclusion criteria, operative techniques and details, and rehabilitation timelines for slope-reducing osteotomies with concomitant primary or revision anterior cruciate ligament (ACLR) and (2) summarize the radiographic and clinical outcomes that follow these types of surgeries.

METHODS

Three databases (MEDLINE, PubMed, and EMBASE) were searched on December 22, 2024, for studies with patients undergoing ACLR with concomitant slope-reducing osteotomy. The authors adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Revised Assessment of Multiple Systematic Reviews guidelines and the Cochrane Handbook for Systematic Reviews of Interventions.

RESULTS

Six case series (Level IV) comprising 193 patients (27.5% female) with a mean age of 28.5 (range of means, 26.9-29.6) years were included. Four of 6 studies (66.7%) reported an indication for slope-reducing osteotomy, being a posterior tibial slope of 12° in revision or re-revision cases. Typical exclusion criteria for osteotomy reported by 5 studies included hyperextension of 5° to 10° or hypermobility (4 studies) and concomitant osteoarthritis (3 studies). Lysholm, Tegner, and visual analog scale scores all statistically increased postoperatively. Rates of return to sport at any level ranged from 81.3% to 100% and 25% to 100%, respectively. Graft failure rates in all studies ranged from 0% to 13%. Rates of recurvatum postoperatively ranged from 15% to 44%. Rates of hardware irritation/removal ranged from 0% to 46.2%.

CONCLUSIONS

The most common indication for slope-reducing osteotomies with concurrent ACLR is in the revision setting in patients with a posterior tibial slope above 12°. Slope-reducing osteotomies with ACLR improve patient-reported outcome measures postoperatively and have low rates of instability and retear rates. Complications with osteotomy include postoperative recurvatum, postoperative hyperextension, and hardware removal.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.

Increased anterior tibial subluxation and differences between anterior tibial subluxation in the lateral and medial compartments are associated with failure of primary anterior cruciate ligament reconstruction: A systematic review and meta-analysis

PURPOSE

The purpose of this study is to investigate whether increased anterior tibial subluxation (ATS) and differences between ATS in the lateral and medial compartments (ATSL-M) are associated with primary anterior cruciate ligament (ACL) reconstruction (ACLR) failure.

METHODS

PubMed, Scopus, Embase and Web of Science were systematically searched from their inception through 21 November 2023. The focus was on comparative studies reporting ATS in patients who experienced primary ACLR failure, in contrast to patients after primary ACLR with no evidence of graft failure. A random-effects model was employed to calculate the overall standardized mean difference between the two groups.

RESULTS

A total of eight studies involving 963 patients were included in the final review. Three studies (64 cases and 171 controls) measured ATS on radiographs. The failed ACLR group exhibited a significantly increased ATS on radiographs compared to the control group (p < 0.001). Six studies (324 cases and 488 controls) measured lateral ATS on magnetic resonance imaging and five of them (285 cases and 374 controls) also measured medial ATS. The average values of lateral and medial ATS, as well as ATSL-M, were calculated and compared between the two groups. The failed ACLR group demonstrated significantly increased lateral (p < 0.001) and medial ATS (p < 0.001), the average value of lateral and medial ATS (p < 0.001) and ATSL-M (p = 0.039) compared to the control group.

CONCLUSION

Increased ATS and ATSL-M are associated with primary ACLR failure. The measurement of tibiofemoral position shows promise for its application in preoperative planning and postoperative management of ACLR.

LEVEL OF EVIDENCE

Level III.

Indicaciones y planificación de la revisión en dos tiempos de la cirugía del ligamento cruzado anterior: revisión narrativa

El aumento en las cirugías de reconstrucción del ligamento cruzado anterior (RLCA) ha generado un incremento proporcional en las revisiones quirúrgicas. Estadísticas canadienses estiman aproximadamente 13 000 revisiones anuales, mientras que en EE. UU. se reporta una incidencia entre el 4.1 y el 13.3 % de todas las RLCA.El éxito de una cirugía de revisión depende de un enfoque sistemático que permita identificar la causa de la falla, como una re-rotura o inestabilidad persistente, y planificar el procedimiento definitivo. Si bien la mayoría de estas revisiones se realizan en un solo tiempo, entre el 8 y el 9 % requieren un abordaje en dos tiempos. Esta decisión depende de factores como la calidad ósea, el tamaño y la posición de los túneles, el método de fijación previo y la presencia de lesiones asociadas.La principal indicación para una revisión en dos tiempos es la osteólisis con túneles mayores a 14 mm o el riesgo de convergencia entre los túneles primarios y de revisión. En este artículo se presenta una revisión narrativa sobre las indicaciones y la planificación quirúrgica de las revisiones del LCA en dos tiempos.En conclusión, existe evidencia limitada, y en general de corto plazo, sobre los resultados de la reconstrucción del LCA en revisiones de dos etapas. A pesar de estas suelen realizarse en casos más complejos, los resultados reportados mostraron resultados clínicos comparables. Nivel de Evidencia: V

When is anterolateral complex augmentation indicated? Perspectives from the 2024 Freddie Fu Panther Sports Medicine Symposium

PURPOSE

This study aimed to determine the trends and indications for anterolateral complex augmentation during anterior cruciate ligament reconstruction (ACL-R) among international orthopedic sports surgeons.

METHODS

An electronically distributed survey was sent out to international surgeons with high-volume experience in complex ligament reconstructions and revision surgery attending the 2024 Freddie Fu Panther Sports Medicine Symposium. The survey was sent prior to the meeting with questions related to the use of lateral extra-articular tenodesis (LET) or anterolateral ligament reconstruction (ALL-R) during ACL-R. Sessions pertaining to anterolateral complex augmentation were held during the symposium to inform about current clinical practices among attendees.

RESULTS

A total of 49 surgeons were identified from 5 different geographic regions prior to the meeting date and were sent an electronic survey, of which 48 responded (98% response rate). Among the surgeons who reported performing anterolateral complex augmentation procedures (n = 45), a total of 39 (87%) respondents reported using only the LET technique, 2 (4%) reported using only the ALL-R technique, and 4 (9%) reported using both techniques during ACL-R. The most common indication for anterolateral complex augmentation was a high-grade pivot shift, which 39 of 43 (91%) respondents ranked in their top 3 indications. In the setting of primary ACL-R, respondents added LET when using hamstring tendon autograft in 38% of cases on average compared with 34% of cases when using either bone-patellar tendon-bone autograft or quadriceps tendon autograft. In the setting of revision ACL-R, LET was added in an average of 68% of cases for a first-time revision ACL-R and in 84% of cases for a multiple-revision ACL-R.

CONCLUSION

The most common indication for ACL-R with anterolateral complex augmentation was a high-grade pivot shift and most respondents preferred LET over ALL-R. Respondents performed LET in a comparable percentage of cases of primary ACL-R using hamstring tendon, bone-patellar tendon-bone, and quadriceps tendon autografts, and this number increased with the number of revision ACL-Rs. Based on the results of this survey, surgeons may consider adding LET in cases of revision ACL-R or in patients with a high-grade pivot shift.

LEVEL OF EVIDENCE

Level V.

Increased posterior tibial slope is a risk factor for anterior cruciate ligament injury and graft failure after reconstruction: A systematic review

IMPORTANCE

Anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) graft failure are important clinical concerns that result in long recovery periods, potential long-term knee instability, and poor patient outcomes. Identifying risk factors such as posterior tibial slope (PTS), meniscal slope (MS), and meniscal bone angle (MBA) is important for improving risk stratification, guiding management decisions, and reducing the incidence of both ACL injury and ACLR graft failure.

OBJECTIVE

This systematic review and meta-analysis aim to determine whether increased PTS, increased MS, and decreased MBA serve as independent predictors of both ACL injury and ACLR graft failure.

EVIDENCE REVIEW

A comprehensive search of the literature was conducted following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. For evaluating ACL injury, the review included comparative studies measuring PTS, MS, or MBA between ACL injury patients and ACL-intact controls. For ACLR graft failure, studies comparing these measurements between patients with ACLR graft failures and those with successful ACLR outcomes were included. Data were pooled using a random-effects model to calculate the overall mean difference (MD) between groups.

FINDINGS

Out of 1,683 initially identified studies, 75 studies were selected for detailed analysis, 53 analyzing ACL injury and 24 studies analyzing ACLR graft failure. The meta-analysis revealed that increased PTS significantly increases the risk of both ACL injury (MD 1.64°; 95% CI: 1.08-2.20, p ​< ​0.01) and ACLR graft failure (MD 1.76°; 95% CI: 1.03-2.48, p ​< ​0.01). This is statistically significant for both lateral and medial PTS, and across both radiograph and magnetic resonance imaging. A higher lateral MS (MD 3.25°; 95% CI: 1.70-4.80, p ​< ​0.01) and a lower lateral MBA (MD -3.85°; 95% CI: -6.38-1.32, p ​< ​0.01) were also significantly associated with an increased risk of ACL injury. However, no statistically significant differences were observed for MS or MBA between ACLR graft failure and successful ACLR groups.

CONCLUSION AND RELEVANCE

The findings indicate that increased PTS, whether measured medially or laterally, is a statistically significant risk factor for both ACL injury and ACLR graft failure. Additionally, increased lateral MS and decreased lateral MBA are associated with ACL injury. This evidence supports the consideration of tibial slope in risk assessment, preoperative planning, and surgical decision-making for both prevention of ACL injury and ACLR procedures. Further research is necessary to fully understand the role of MS and MBA in ACL injury.

LEVEL OF EVIDENCE

Level IV; systematic review of level III-IV studies.

Age not a primary risk factor for ACL injury-A comprehensive review of ACL injury and reinjury risk factors confounded by young patient age

Revision surgery after anterior cruciate ligament reconstruction (ACL-R) is hypothesized to be the result of an interplay between factors associated with the anatomy, physiological characteristics and environment of the patient. The multifactorial nature of revision ACL-R risk is difficult to quantify, and evidence regarding the independent roles of potentially important variables is inconsistent throughout the literature. Young patient age is often cited as one of the most prominent risk factors for reinjury after ACL-R. However, the association between a non-modifiable variable such as patient age and revision ACL-R risk is likely to be a spurious correlation due to the confounding effect of more important variables. From the perspective of healthcare professionals aiming to mitigate revision ACL-R risk through targeted interventions, awareness of factors like generalized joint hypermobility, bone morphology, muscle strength imbalances, and genetic factors is critical for the individualized risk assessment of patients with ACL injury. The aim of this current concepts article is to raise awareness of the essential anatomical, physiological, and activity-related risk factors associated with ACL injury and reinjury risk that are likely captured and confounded by patient age. LEVEL OF EVIDENCE: Level V.

Editorial Commentary: Unlike Modifiable Factors, Non-modifiable Risk Factors for Anterior Cruciate Ligament Injury Including Lateral Femoral Condyle Ratio and Lateral Femoral Condyle Index Have Low Clinical Relevance

Risk factor mitigation is of the utmost concern in the prevention of primary anterior cruciate ligament (ACL) injuries. Known anatomic risks for ACL injury include varus deformity of the knee, increased posterior tibial slope, decreased femoral notch width, and more recently, increased lateral femoral condyle ratio (LFCR) and decreased lateral femoral condyle index. Whereas some authors recommend knee osteotomy in the revision setting to correct deformities of the proximal tibia, osteotomy to decrease posterior femoral condyle depth has not been described, to my knowledge, although lateral extra-articular tenodesis in cases of an increased LFCR during revision ACL reconstruction has been recommended. Increased posterior femoral condyle depth as measured by the LFCR is non-modifiable and therefore lacks clinical use in the prevention of primary ACL injuries. Providers should focus on modifiable factors such as quadriceps strength, core strengthening, and altered landing mechanics in the prevention of primary ACL injury.

Slope-Reducing Tibial Plateau-Leveling Osteotomy

Increased posterior tibial slope (PTS) is a risk factor for anterior cruciate ligament (ACL) tear and ACL reconstruction failure. Anterior closing-wedge osteotomy (ACWO) decreases the PTS and the risk of reinjury after revision ACL reconstruction. ACWO techniques include supratubercular, transtubercular, or infratubercular. However, there are limitations to the amount of slope correction an ACWO can achieve in the context of a massively abnormal slope. If the necessary slope correction is greater than 20°, a supratubercular ACWO cannot achieve the required correction without high risk of brittle fixation, a transtubercular ACWO would introduce increased morbidity of a secondary osteotomy and change the biomechanics of the patellofemoral joint resulting in significant patella alta, and an infratubercular ACWO would require a major anterior tibial metaphysodiaphyseal resection. The tibial plateau leveling osteotomy (TPLO) is an alternative curved osteotomy commonly used in canines that avoids the adverse events associated with a large ACWO. Further benefits of TPLO for massive slope correction include improved maintenance of native soft-tissue tension, avoidance of major recurvatum, and the ability to control the correct degree. We describe an open technique for a TPLO to decrease the PTS and the risk of recurrent ACL injury.

Increased posterior tibial slope leads to altered pressure distribution in the lateral tibial plateau-A biomechanical in-vitro study

PURPOSE

The aim of this study is to investigate the impact of increased posterior tibial slope (PTS) on pressure distribution in the medial and lateral tibial plateau. The focus is on compartment-specific effects and potential correlations with cartilage damage, due to altered anterior tibial translation caused by increased PTS.

METHOD

Ten freshly frozen knee specimens were prepared and subjected to biomechanical testing. PTS was modified by inserting 5°, 10°, 15° and 20° polylactic acid wedges into osteotomy gaps. Pressure distribution was measured using Tekscan's Pressure Mapping Sensor 5040™ beneath the menisci at varying PTS angles. The kinetic data were tracked using the Optotrak Certus® system. Statistical analyses were employed to evaluate the pressure shifts and their significance.

RESULTS

The study revealed that increased PTS significantly shifted the pressure point anteriorly on the lateral tibial plateau, while no significant changes were observed on the medial plateau. The analysis of tibial translation showed a corresponding rise in anterior translation with increasing PTS, especially at higher angles.

CONCLUSION

Increased PTS, particularly above 10°, induces significant anterior translation and altered pressure distribution, primarily affecting the lateral tibial plateau. These findings support the hypothesis that elevated PTS contributes to biomechanical stresses in the knee, potentially increasing the risk of lateral compartment cartilage degeneration. These results highlight the importance of considering PTS in clinical assessments and interventions aimed at optimizing knee joint health.

LEVEL OF EVIDENCE

Level IV.

Infratuberosity Anterior Closing-Wedge High Tibial Osteotomy for Slope Correction in Anterior Cruciate Ligament-Deficient Knees

Graft failure after anterior cruciate ligament reconstruction is multifactorial, with increased tibia slope identified as one of the risk factors. Several slope-correcting osteotomies have been proposed to address this in revision surgery, with most of the procedures using a supratuberosity or transtuberosity approach. Although satisfactory results have been presented, severe complications involving the extensor mechanism can occur. In this Technical Note, an infratuberosity anterior closing-wedge high tibial osteotomy is demonstrated for slope correction in anterior cruciate ligament-deficient knees in the revision setting.

Anatomic Risk Factors for Initial and Secondary Noncontact Anterior Cruciate Ligament Injury: A Prospective Cohort Study in 880 Female Elite Handball and Soccer Players

BACKGROUND

Anterior cruciate ligament (ACL) injury is one of the most severe injuries for athletes. It is important to identify risk factors because a better understanding of injury causation can help inform athletes about risk and increase their understanding of and motivation for injury prevention.

PURPOSE

To investigate the relationship between anatomic factors and risk for future noncontact ACL injuries.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 870, excluding 9 players with a new contact ACL injury and a player with a new noncontact ACL injury just before the testing, female elite handball and soccer players-86 of whom had a history of ACL injury-underwent measurements of anthropometrics, alignment, joint laxity, and mobility, including leg length, knee alignment, knee anteroposterior laxity, generalized joint hypermobility, genu recurvatum, and hip anteversion. All ACL injuries among the tested players were recorded prospectively. Welch t tests and chi-square tests were used for comparison between the groups (new injury group, which sustained a new ACL injury in the follow-up period, and no new injury group).

RESULTS

An overall 64 new noncontact ACL injuries were registered. No differences were found between athletes with and without a new ACL injury among most of the measured variables. However, static knee valgus was significantly higher in the new injury group than in the no new injury group among all players (mean difference [MD], 0.9°; P = .007), and this tendency was greater in players with a previous ACL injury (MD, 2.1°; P = .002). Players with secondary injury also had a higher degree of knee hyperextension when compared with those previously injured who did not have a secondary injury (MD, 1.6°; P = .007).

CONCLUSION

The anatomic factors that we investigated had a weak or no association with risk for an index noncontact ACL injury. Increased static knee valgus was associated with an increased risk for noncontact ACL injury, in particular for secondary injury. Furthermore, hyperextension of the knee was a risk factor for secondary ACL injury.

Enhanced reliability and time efficiency of deep learning-based posterior tibial slope measurement over manual techniques

PURPOSE

Multifaceted factors contribute to inferior outcomes following anterior cruciate ligament (ACL) reconstruction surgery. A particular focus is placed on the posterior tibial slope (PTS). This study introduces the integration of machine learning and artificial intelligence (AI) for efficient measurements of tibial slopes on magnetic resonance imaging images as a promising solution. This advancement aims to enhance risk stratification, diagnostic insights, intervention prognosis and surgical planning for ACL injuries.

METHODS

Images and demographic information from 120 patients who underwent ACL reconstruction surgery were used for this study. An AI-driven model was developed to measure the posterior lateral tibial slope using the YOLOv8 algorithm. The accuracy of the lateral tibial slope, medial tibial slope and tibial longitudinal axis measurements was assessed, and the results reached high levels of reliability. This study employed machine learning and AI techniques to provide objective, consistent and efficient measurements of tibial slopes on MR images.

RESULTS

Three distinct models were developed to derive AI-based measurements. The study results revealed a substantial correlation between the measurements obtained from the AI models and those obtained by the orthopaedic surgeon across three parameters: lateral tibial slope, medial tibial slope and tibial longitudinal axis. Specifically, the Pearson correlation coefficients were 0.673, 0.850 and 0.839, respectively. The Spearman rank correlation coefficients were 0.736, 0.861 and 0.738, respectively. Additionally, the interclass correlation coefficients were 0.63, 0.84 and 0.84, respectively.

CONCLUSION

This study establishes that the deep learning-based method for measuring posterior tibial slopes strongly correlates with the evaluations of expert orthopaedic surgeons. The time efficiency and consistency of this technique suggest its utility in clinical practice, promising to enhance workflow, risk assessment and the customization of patient treatment plans.

LEVEL OF EVIDENCE

Level III, cross-sectional diagnostic study.

Guided Growth for Posterior Tibial Slope Correction Followed by ACL Reconstruction in an Adolescent Male: A Case Report

CASE

A 13-year-old adolescent boy presented with chronic anterior cruciate ligament (ACL) insufficiency and prior medial meniscectomy. Radiographic evaluation revealed a posterior tibial slope (PTS) of 20°, putting him at high risk of reinjury following ACL reconstruction (ACLR). Guided growth using anteriorly placed eight plates was used for 9 months, which reduced his PTS to 6°. Two months following plate removal, the patient underwent ACLR with lateral extra-articular tenodesis.

CONCLUSION

This previously proposed but never reported approach suggests that guided growth is a viable option to correct excessive PTS before ACLR in skeletally immature patients.

Does Tibial Plateau Slope and Depth Influence ACL Strain In Vivo?

Background

The anterior cruciate ligament (ACL) is loaded under tension when the tibia translates anteriorly relative to the femur. The shape of the articular surfaces of the tibiofemoral joint may influence the amount of anterior tibial translation under compressive loading. Thus, a steep lateral tibial plateau and a shallow medial plateau are thought to be risk factors for ACL injury.

Purpose/Hypothesis

The purpose of this study was to evaluate whether tibial plateau slope and depth influence peak ACL strain during a single-leg jump. We hypothesized that there would be a significant correlation between tibial plateau slope and depth with ACL strain.

Study Design

Descriptive laboratory study.

Methods

A total of 17 healthy participants (8 male, 9 female) were assessed using magnetic resonance imaging (MRI) and high-speed biplanar radiography to obtain peak ACL strain during a single-leg jump. Two orthopaedic surgeons used the sagittal plane MRI scans to measure the medial and lateral tibial plateau slopes and the medial tibial plateau depth. The intraclass correlation coefficient was used to assess measurement reliability, and the Spearman rank correlation was used to evaluate the relationship between measurements of tibial morphology and peak ACL strain during the single-leg jump.

Results

The overall range of intraclass correlation coefficients for intra- and interrater reliability of the medial and lateral tibial plateau slopes and medial plateau depth was 0.59 to 0.97. No significant correlations were found between peak ACL strain and any of the slope or depth measurements.

Conclusion

In this cohort of healthy participants, correlations between any of the tibial plateau measurements with peak ACL strain during a single-leg jump were not detected. These findings are consistent with prior work, suggesting that tibial plateau slope and depth may not be linked to risk for ACL rupture. However, it is possible that tibial plateau morphology may interact with other factors to increase ACL injury risk or that individuals with extreme slope angles may produce differing results.

Clinical Relevance

This study enhances the knowledge of the loading mechanisms for the ACL and thus improves the understanding of risk factors for ACL injury.

Editorial Commentary: Increased Tibial Slope and Decreased Medial Proximal Tibial Angle Negatively Affect Anterior Cruciate Ligament Graft Maturation: Objective Evidence on When to Add a Lateral Extra-Articular Augmentation Procedure to a Soft-Tissue Anterior Cruciate Ligament Reconstruction

Recent anterior cruciate ligament (ACL) research focuses on risk factors for ACL graft failure and techniques and augmentations to limit failure. One of the most recognized risk factors is sagittal malalignment in the form of high posterior tibial slope (PTS), especially PTS ≥12°, which leads to increased force through the ACL and ACL graft. To reduce the risk associated with increased PTS, lateral augmentation techniques, typically either a lateral extra-articular tenodesis or an anterolateral ligament reconstruction, improve clinical outcomes, and the authors preferred graft choice, particularly in such cases, is bone-patellar tendon-bone autograft. Furthermore, in revision cases, there exists a strong argument to perform a slope reducing osteotomy to correct bony malalignment which, if left untreated, could lead to ACL graft failure. Slope-reducing osteotomies are reported to significantly decrease anterior tibial translation and forces on the ACL graft. Coronal malalignment is also a risk factor for ACL failure (although not as extensively studied as sagittal alignment). Both varus and valgus alignment of the knee can lead to increased forces through the ACL or ACL graft compared with knees in neutral alignment, and workup requires proper lateral and long-leg anteroposterior radiographs to determine sagittal and coronal alignment and guide treatment algorithms. Recent research shows that decreased medial proximal tibial angle of the knee (increasing varus alignment of the tibia) may delay graft maturation. However, there is yet to be a consensus about what exactly contributes to ACL graft failure in the coronal plane and what is the best treatment option, especially in the primary setting when an osteotomy is not indicated. Again, we recommend bone-patellar tendon-bone autograft as our preferred graft choice unless contraindicated by skeletal immaturity.

Slope-Reducing Proximal Tibial Osteotomy Improves Outcomes in Anterior Cruciate Ligament Reconstruction Patients With Elevated Posterior Tibial Slope, Especially Revisions and Posterior Tibial Slope ≥12

PURPOSE

To explore the indications, outcomes, and complications related to slope-reducing osteotomies in the setting of anterior cruciate ligament (ACL) tears or graft failure. A secondary aim was to create an algorithm on the basis of the current literature and authors' opinions.

METHODS

This study was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Studies were included if they reported on outcomes related to slope-reducing osteotomies both for primary ACL tears and revision ACL graft tears. The studies were analyzed to determine the radiographic outcomes, patient-reported outcomes (PROs), physical examination findings, and complications. Statistical analysis could not be performed because of the heterogeneity between studies.

RESULTS

A total of 148 studies were screened for inclusion in this systematic review and after full-text review, a total of 16 studies were included in this systematic review. Fourteen of the studies reported on pre- versus postoperative posterior tibial slope (PTS) and all but one reported significant decrease in PTS. Seven studies reported on pre- versus postoperative PROs, and all studies reported significant improvements in postoperative scores. Anterior tibial translation was measured in 8 studies, and all reported a significant decrease in anterior tibial translation postoperatively. The most common complication was postoperative hyperextension and irritation from hardware. Irritation from hardware was only reported in studies that used plates to fixate the osteotomy.

CONCLUSIONS

In conclusion, slope-reducing proximal tibial osteotomies performed concurrently or as a second-stage surgery with an anterior cruciate ligament reconstruction (ACLR) resulted in improved PROs and decreased ACLR failure rates. Slope-reducing proximal tibial osteotomies are an important treatment consideration for those patients with an increased PTS, especially for patients with a failed ACLR and a PTS ≥12°, to reduce the risk of ACLR failure.

LEVEL OF EVIDENCE

Level IV, systematic review of Level IV studies.

Higher Posterior Tibial Slope and Lower Medial Proximal Tibial Angle of the Knee Are Associated With Delayed Graft Maturation After Anterior Cruciate Ligament Reconstruction Surgery With Hamstring Autograft

PURPOSE

To relate bone shape with anterior cruciate ligament (ACL) graft maturation, as evaluated by quantitative magnetic resonance imaging.

METHODS

We retrospectively evaluated patients aged 18 to 60 years who underwent ACL reconstruction with a hamstring autograft with doubled semitendinosus and gracilis at our institution between 2018 and 2020 with isolated ACL injuries. All patients had a minimum follow-up period of 2 years. To evaluate alignment, radiographs of the knee were taken preoperatively. Postoperative 3T magnetic resonance imaging and patient-reported outcome scores were acquired at 2 years after surgery. A combined T1ρ/T2 quantification sequence and a 3-dimensional multiecho ultrashort echo time (UTE) cone sequence were obtained in a sagittal-oblique plane for better assessment of the ACL graft. After acquiring images, a manual segmentation for the ACL graft was performed to assess T1ρ, T2, and UTE T2∗ relaxation times. Correlations between radiographic parameters or patient-reported outcome scores and T1ρ, T2, and UTE T2∗ values were tested with Pearson correlation coefficients. Significance was defined as P < .05.

RESULTS

Participants were 28 patients (12 men and 16 women) who had a mean (SD) age of 34.3 (8.5) years and body mass index of 24.4 (4.5). A significant correlation was found between the preoperative posterior tibial slope (PTS) and the T1ρ, T2, and UTE T2∗ relaxation times (r = 0.41, P = .033; r = 0.47, P = .014; and r = 0.41, P = .030), indicating inferior graft maturation in patients with a higher PTS. Furthermore, a negative correlation was identified between the preoperative medial proximal tibial angle and the T1ρ, T2, and UTE T2∗ relaxation times (r = -0.39, P = .039; r = -0.46, P = .018; and r = -0.43, P = .024), indicating inferior graft maturation in patients with greater varus knee alignment.

CONCLUSIONS

The study findings suggest that an increased PTS and a lower medial proximal tibial angle are associated with inferior graft maturation as per T1ρ, T2, and UTE T2∗ imaging at 2 years post-ACL reconstruction.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Slope Osteotomies in the Setting of Anterior Cruciate Ligament Deficiency

➤ Posterior tibial slope (PTS) of ≥12° represents an important risk factor for both anterior cruciate ligament (ACL) injury and ACL reconstruction failure.➤ PTS measurements can significantly differ on the basis of the imaging modality and the measurement technique used. PTS should be measured on strictly lateral radiographs, with a recommended proximal tibial length of 15 cm in the image. The PTS measurement can be made by placing 2 circles to define the proximal tibial axis, 1 just below the tibial tubercle and another 10 cm below it. PTS measurements are underestimated when made on magnetic resonance imaging and computed tomography.➤ Slope-reducing osteotomies can be performed using a (1) supratuberosity, (2) tubercle-reflecting transtuberosity, or (3) infratuberosity method. The correction target remains a topic of debate. Although it is controversial, some authors recommend overcorrecting the tibial slope slightly to a range of 4° to 6°. For instance, if the initial slope is 12°, a correction of 6° to 8° should be performed, given the target tibial slope of 4° to 6°.➤ Clinical outcomes following slope-reducing osteotomies have been favorable. However, potential complications, limited data with regard to the impact of slope-reducing osteotomies on osteoarthritis, and uncertainty with regard to the effects on the patellofemoral joint are notable concerns.➤ Patients with complex deformities may need biplanar osteotomies to comprehensively address the condition.

Around-the-knee osteotomies part II: Surgical indications, techniques and outcomes - State of the art

Recent advances in surgical techniques and planning for knee-based osteotomies have led to improvements in addressing lower extremity malalignment. Part 1 of this review presented the biomechanical and clinical rationale of osteotomies, emphasizing the importance of osteotomies for restoring normal knee kinematics. In Part 2 of this review, indications, surgical technique and outcomes of osteotomies to correct coronal, sagittal and axial plane deformities will be examined. Traditional high tibial and distal femoral osteotomies will be discussed in addition to more recent advanced techniques including biplanar corrections and double-level osteotomies, as well as slope-correcting osteotomies. Patient-specific instrumentation and its use in more complex corrections will also be addressed.

Increased Lateral Femoral Condyle Ratio Measured by Magnetic Resonance Imaging Is Associated With Anterior Cruciate Ligament Rerupture

PURPOSE

To investigate the association between lateral femoral condyle ratio (LFCR) measured by magnetic resonance imaging (MRI) and anterior cruciate ligament (ACL) rerupture after anatomic ACL reconstruction (ACLR) and to compare the diagnostic accuracy between MRI and radiograph measurements.

METHODS

A retrospective review was conducted on patients who underwent anatomic ACLR in our institution between 2015 and 2018. Patients who experienced rerupture after ACLR were identified and matched 1:1 with control patients who showed no evidence of graft failure during a minimum 48-month follow-up. The matching criteria included age, sex, and body mass index. LFCR was measured on MRI scans and radiographs of the affected limb. Patients' characteristics, surgical features, and anatomic measurements were compared between groups. Conditional logistic regression was performed to investigate whether MRI-measured LFCR is a risk factor for ACL rerupture. The optimal cutoff value was determined by receiver operating characteristic curves (ROC). Delong's test was performed to compare the diagnostic accuracy between MRI and radiograph measurements.

RESULTS

A total of 72 patients who sustained ACL rerupture were included and matched with 72 control subjects. Compared to patients with intact ACLR, those who sustained ACL rerupture showed a significant increase in LFCR on MRI scans (63.38% ± 2.26% [95% CI, 62.84%-63.91%] vs 61.10% ± 2.19% [95% CI, 60.59%-61.61%], P < .001). An MRI-measured LFCR >62.18% was set as the cutoff point to discern patients at a higher risk of graft failure after anatomic ACLR, with sensitivity and specificity of 75.0% and 70.8%, respectively. MRI-measured LFCR demonstrated superior diagnostic accuracy during ROC curve analysis, achieving a higher area under the curve compared to radiograph-measured LFCR (0.783 ± 0.051 vs 0.668 ± 0.060, P = .041).

CONCLUSIONS

The study found that MRI-measured LFCR was associated with ACL rerupture. A cutoff value of 62.18% was determined, which can help identify patients at a higher risk of rerupture.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Editorial Commentary: Increased Lateral Femoral Condyle Ratio, Increased Posterior Tibial Slope, and Narrow Notch Width Are all Risk Factors for Anterior Cruciate Ligament Tear, and Anterior Cruciate Ligament Graft Tear

Bony risk factors for anterior cruciate ligament (ACL) injuries have been investigated during past 2 decades. Deep posterior femoral condylar depth, measured by the lateral femoral condyle ratio, influences anterolateral instability and the graft survival following ACL reconstructions. Before planning of revision ACL reconstruction, other bony risk factors, including the posterior tibial slope and intercondylar notch width, should be carefully evaluated to protect the ACL graft.

Anterior Proximal Tibial Screw Hemiepiphysiodesis Decreases Posterior Tibial Slope in Knee Flexion Contracture: A Case Report

CASE

A 13-year-old adolescent boy with hemiplegic cerebral palsy suffering from fixed knee flexion deformity of 10° despite extensive conservative treatment. Owing to a posterior tibial slope (PTS) of 16°, anterior hemiepiphysiodesis was applied to the proximal tibia. The 2 screws were removed after 9 months. Final follow-up at 16 months showed complete knee extension and a PTS of 4°.

CONCLUSION

The presented technique is a good alternative in knee flexion deformity with an increased PTS and has surprisingly not been described in the literature. This might be worth considering for other pathologies such as pediatric anterior cruciate ligament injury with an increased PTS.

Four to 6° Is the Target Posterior Tibial Slope After Tibial Deflection Osteotomy According to the Knee Static Anterior Tibial Translation

PURPOSE

To correlate changes in posterior tibial slope (PTS) with changes to static anterior tibial translation (SATT) with tibial deflexion osteotomy (TDO), in order to define a target postoperative tibial slope based on postoperative SATT.

METHODS

We reviewed a consecutive series of primary and revision anterior cruciate ligament reconstruction with TDO between 2011 and 2022. PTS and SATT were measured pre- and postoperatively directly from the radiographs by 2 independent reviewers. Regression analysis was performed to investigate the relationship of postoperative SATT with PTS, gender, graft type, and meniscal injury.

RESULTS

A total of 48 patients were included in this study. The mean (SD) decrease in PTS and SATT was 8.85° (3.03°; 12.5° to 3.59°, P < .01), and 7.93 mm (3.68; 5.37 to -2.55 mm, P < .01), respectively. Upon univariate analysis, the only factor influencing ΔSATT was ΔPTS. For each 1° of decreased slope, SATT was reduced by 0.46 mm. The mean (SD) PTS for a negative SATT was 2.81° (2.78°) compared to 5.09° (3.25°) for a SATT of 0 to 5mm (P < .01).

CONCLUSIONS

This study reports weightbearing SATT in association with PTS after TDO. The TDO successfully reduced the SATT, with the change in PTS the only significant predictor of postoperative SATT. Based on our results, our previously held target of 2° to 5° PTS overcorrected the SATT. Therefore, considering as a goal 0 to 5 mm of SATT, we suggest a new target of 4° to 6° PTS.

LEVEL OF EVIDENCE

Level IV, retrospective cohort study.

Decreased posterior tibial slope is a risk factor for primary posterior cruciate ligament rupture and posterior cruciate ligament reconstruction failure: A systematic review

PURPOSE

To determine bony knee morphological factors associated with primary posterior cruciate ligament (PCL) rupture or PCL graft failure after PCL reconstruction.

METHODS

Three databases, namely MEDLINE, PubMed and EMBASE, were searched on 30th May 2023. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data such as receiver operating characteristic curve parameters, as well as p-values for comparisons of values between patients with PCL pathology and control patients, were recorded.

RESULTS

Nine studies comprising 1054 patients were included. Four studies reported that patients with PCL injury had flatter medial posterior tibial slopes (MTS) than controls, with mean values of 4.3 (range: 3.0-7.0) and 6.5 (range: 5.0-9.2) degrees, respectively. Two studies reported an MTS cutoff value ranging below 3.90-3.93° being a significant risk factor for primary PCL rupture or PCL graft failure. Two studies reported that shallow medial tibial depths were associated with primary PCL rupture, with mean values of 2.1 (range: 2.0-2.2) and 2.6 (range: 2.4-2.7) mm in PCL injury and control groups, respectively. Stenotic intercondylar notches and femoral condylar width were not consistently associated with PCL injuries.

CONCLUSION

Decreased MTS is associated with primary PCL rupture and graft failure after PCL reconstruction with values below 3.93° being considered as a significant risk factor. Less common risk factors include shallow medial tibial depth, while femoral condylar width and parameters with regards to the intercondylar notch, such as notch width, notch width index and intercondylar notch volume, demonstrated conflicting associations with primary or secondary PCL injuries.

LEVEL OF EVIDENCE

Level III.

Management of anterior cruciate ligament revision in adults: the 2022 ESSKA consensus part III-indications for different clinical scenarios using the RAND/UCLA appropriateness method

PURPOSE

The aim of the ESSKA 2022 consensus Part III was to develop patient-focused, contemporary, evidence-based, guidelines on the indications for revision anterior cruciate ligament surgery (ACLRev).

METHODS

The RAND/UCLA Appropriateness Method (RAM) was used to provide recommendations on the appropriateness of surgical treatment versus conservative treatment in different clinical scenarios based on current scientific evidence in conjunction with expert opinion. A core panel defined the clinical scenarios with a moderator and then guided a panel of 17 voting experts through the RAM tasks. Through a two-step voting process, the panel established a consensus as to the appropriateness of ACLRev for each scenario based on a nine-point Likert scale (in which a score in the range 1-3 was considered 'inappropriate', 4-6 'uncertain', and 7-9 'appropriate').

RESULTS

The criteria used to define the scenarios were: age (18-35 years vs 36-50 years vs 51-60 years), sports activity and expectation (Tegner 0-3 vs 4-6 vs 7-10), instability symptoms (yes vs no), meniscus status (functional vs repairable vs non-functional meniscus), and osteoarthritis (OA) (Kellgren-Lawrence [KL] grade 0-I-II vs grade III). Based on these variables, a set of 108 clinical scenarios was developed. ACLRev was considered appropriate in 58%, inappropriate in 12% (meaning conservative treatment is indicated), and uncertain in 30%. Experts considered ACLRev appropriate for patients with instability symptoms, aged ≤ 50 years, regardless of sports activity level, meniscus status, and OA grade. Results were much more controversial in patients without instability symptoms, while higher inappropriateness was related to scenarios with older age (51-60 years), low sporting expectation, non-functional meniscus, and knee OA (KL III).

CONCLUSION

This expert consensus establishes guidelines as to the appropriateness of ACLRev based on defined criteria and provides a useful reference for clinical practice in determining treatment indications.

LEVEL OF EVIDENCE

II.

Bone morphology features associated with knee kinematics may not be predictive of ACL elongation during high-demand activities

PURPOSE

Bony morphology has been proposed as a potential risk factor for anterior cruciate ligament (ACL) injury. The relationship between bony morphology, knee kinematics, and ACL elongation during high-demand activities remains unclear. The purpose of this study was to determine if bone morphology features that have been associated with ACL injury risk and knee kinematics are also predictive of ACL elongation during fast running and double-legged drop jump.

METHODS

Nineteen healthy athletes performed fast running and double-legged drop jump within a biplane radiography imaging system. Knee kinematics and ACL elongation were measured bilaterally after using a validated registration process to track bone motion in the radiographs and after identifying ACL attachment sites on magnetic resonance imaging (MRI). Bony morphological features of lateral posterior tibial slope (LPTS), medial tibial plateau (MTP) depth, and lateral femoral condyle anteroposterior width (LCAP)/lateral tibial plateau anteroposterior width (TPAP) were measured on MRI. Relationships between bony morphology and knee kinematics or ACL elongation were identified using multiple linear regression analysis.

RESULTS

No associations between bony morphology and knee kinematics or ACL elongation were observed during fast running. During double-legged drop jump, a greater range of tibiofemoral rotation was associated with a steeper LPTS (β = 0.382, p = 0.012) and a deeper MTP depth (β = 0.331, p = 0.028), and a greater range of anterior tibial translation was associated with a shallower MTP depth (β = - 0.352, p = 0.018) and a larger LCAP/ TPAP (β = 0.441, p = 0.005); however, greater ACL elongation was only associated with a deeper MTP depth (β = 0.456, p = 0.006) at toe-off.

CONCLUSION

These findings indicate that observed relationships between bony morphology and kinematics should not be extrapolated to imply a relationship also exists between those bone morphology features and ACL elongation during high-demand activities. These new findings deepen our understanding of the relationship between bony morphology and ACL elongation during high-demand activities. This knowledge can help identify high-risk patients for whom additional procedures during ACL reconstruction are most appropriate.

Though five-strand hamstring autografts demonstrate greater graft diameter, postoperative outcomes are equivocal to four-strand hamstring autograft preparations: a systematic review and meta-analysis of level I and II studies

PURPOSE

To compare graft dimensions, functional outcomes, and failure rates following anterior cruciate ligament reconstruction (ACLR) with either five-strand or four-strand hamstring autograft options.

METHODS

Three databases (MEDLINE, PubMed, and EMBASE) were searched from inception to 22 April 2023 for level I and II studies comparing five- and four-strand hamstring autografts in ACLR. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on demographics, surgical details and rehabilitation, graft diameter, patient-reported outcome measures (PROMs), and rates of positive Lachman test, positive pivot shift test, and graft rupture were extracted. PROMs included Knee Osteoarthritis and Outcome Score (KOOS) subscales, Lysholm, and International Knee Documentation Committee (IKDC).

RESULTS

One randomized controlled trial (RCT) and four prospective cohort studies with 572 patients were included. Graft diameters were larger in the five-strand group with a mean difference of 0.93 mm (95% CI 0.61 to 1.25, p < 0.001, I2 = 66%). The five-strand group reported statistically higher KOOS ADL subscale and Lysholm scores with a mean difference of 4.85 (95% CI 0.14 to 9.56, p = 0.04, I2 = 19%) and 3.01 (95% CI 0.48 to 5.53, p = 0.02, I2 = 0%), respectively. There were no differences in KOOS symptoms, pain, quality of life, or sports subscales, or IKDC scores. There were no differences in rates of positive Lachman test, positive pivot shift test, or graft rupture with pooled odds ratios of 0.62 (95% CI 0.13 to 2.91, n.s., I2 = 80%), 0.94 (95% CI 0.51 to 1.75, n.s., I2 = 31%), and 2.13 (95% CI 0.38 to 12.06, n.s., I2 = 0%), respectively.

CONCLUSIONS

Although five-stranded hamstring autografts had significantly larger graft diameters compared to four-stranded grafts with a mean difference of 0.93 mm, similar graft rupture rates and clinical laxity assessments were identified following ACLR. While some PROMs were statistically superior in the five-stranded hamstring groups, the threshold for the minimal clinical important difference was not reached indicating similar clinical outcomes overall.

LEVEL OF EVIDENCE

Level II.

Posterior tibial slope, notch width index and tibial tubercle to trochlear groove distance contribute to development of mucoid degeneration of the anterior cruciate ligament: a systematic review

PURPOSE

To determine what knee morphological factors are associated with the development of mucoid degeneration of the anterior cruciate ligament (ACL).

METHODS

Three databases MEDLINE, PubMed and EMBASE were searched from inception to January 29th, 2023 for literature outlining knee morphological factors that potentially lead to the development of mucoid degeneration of the ACL. The authors adhered to the PRISMA and R-AMSTAR guidelines as well as the Cochrane Handbook for Systematic Reviews of Interventions. Data on receiver operating characteristic (ROC) curve parameters such as area under the curve (AUC), sensitivity and specificity, odds ratios, as well as p values for comparisons of values between mucoid degeneration of the ACL and control patients were recorded. The Methodological Index for Non-Randomized Studies (MINORS) score was used for all studies to perform a quality assessment of included studies.

RESULTS

A total of 7 studies comprising 1326 patients (1330 knees) were included in this review. Four studies reported a significant association between increasing posterior tibial slope angles and mucoid degeneration of the ACL presence, with one study specifying that posterolateral tibial slope had a greater association than posteromedial tibial slope. Two studies reported a significant association between lower notch width index values and mucoid degeneration of the ACL presence. One study found that the presence of trochlear dysplasia was correlated with mucoid degeneration of the ACL and two studies found that increased tibial tuberosity-trochlear groove distance (TT-TG) was associated with mucoid degeneration of the ACL.

CONCLUSION

Increased posterior tibial slope, decreased notch width index, and elevated TT-TG and trochlear dysplasia were associated with the presence of mucoid degeneration of the ACL. Information from this review can aid surgeons in understanding what morphological features predispose their patients to the development of mucoid degeneration of the ACL. Identifying what features predispose patients to mucoid degeneration of the ACL can help determine if regular screening or preventative strategies are necessary.

LEVEL OF EVIDENCE

Level III.