Histological evaluation and comparison of the anteromedial and posterolateral bundle of the human anterior cruciate ligament of the osteoarthritic knee joint

The morphology of the femoral footprint of the anterior cruciate ligament changes with aging from a large semicircular shape to a small flat ribbon-like shape

PURPOSE

Compare the differences in the morphology of the ACL femoral footprint between the cadavers of the young and elderly in consideration of the degenerative physiological process that occurs with aging.

METHODS

The femoral footprint of the ACL was dissected in 81 knees of known gender and age (45 male/36 female). They were divided into four groups by age and gender, establishing 50 years as the cut-off point to divide patients by age. Three observers analyzed the femoral footprint dissections, and the shapes were described and classified. The area and morphometric characteristics of the femoral insertion of the ACL were determined and these were compared between genders and age groups.

RESULTS

The femoral footprint of the ACL from the cadavers of males younger than 50 years of age presented a semicircular morphology in 90% of the cases. In males aged more than 50 years, a ribbon-like morphology was found in 96% of the cases. In women less than 50 years old, the semicircular morphology was observed in 93.7% of the cases. In women aged over 50 years old, the ribbon-like morphology was found in 95% of the cases. A significant difference was observed between the prevalence rates of the morphologies, area size and measurements of the younger and older groups (p < 0.001 for both genders).

CONCLUSIONS

The femoral insertion of the ACL presents variations in its morphology, area and morphometric characteristics over time. It goes from a large semicircular shape that almost contacts the posterior articular cartilage to a smaller, flattened ribbon-like shape that moves away from the edge of the articular cartilage. It is bounded anteriorly by the lateral intercondylar ridge. These findings should be considered to avoid employing reconstruction techniques in which femoral tunnels with oval or rectangular shapes are used in patients under 50 years of age because they do not correspond to the morphology of the femoral insertion of the ACL in this age group.

Ligament mechanics of ageing and osteoarthritic human knees

Knee joint ligaments provide stability to the joint by preventing excessive movement. There has been no systematic effort to study the effect of OA and ageing on the mechanical properties of the four major human knee ligaments. This study aims to collate data on the material properties of the anterior (ACL) and posterior (PCL) cruciate ligaments, medial (MCL) and lateral (LCL) collateral ligaments. Bone-ligament-bone specimens from twelve cadaveric human knee joints were extracted for this study. The cadaveric knee joints were previously collected to study ageing and OA on bone and cartilage material properties; therefore, combining our previous bone and cartilage data with the new ligament data from this study will facilitate subject-specific whole-joint modelling studies. The bone-ligament-bone specimens were tested under tensile loading to failure, determining material parameters including yield and ultimate (failure) stress and strain, secant modulus, tangent modulus, and stiffness. There were significant negative correlations between age and ACL yield stress (p = 0.03), ACL failure stress (p = 0.02), PCL secant (p = 0.02) and tangent (p = 0.02) modulus, and LCL stiffness (p = 0.046). Significant negative correlations were also found between OA grades and ACL yield stress (p = 0.02) and strain (p = 0.03), and LCL failure stress (p = 0.048). However, changes in age or OA grade did not show a statistically significant correlation with the MCL tensile parameters. Due to the small sample size, the combined effect of age and the presence of OA could not be statistically derived. This research is the first to report tensile properties of the four major human knee ligaments from a diverse demographic. When combined with our previous findings on bone and cartilage for the same twelve knee cadavers, the current ligament study supports the conceptualisation of OA as a whole-joint disease that impairs the integrity of many peri-articular tissues within the knee. The subject-specific data pool consisting of the material properties of the four major knee ligaments, subchondral and trabecular bones and articular cartilage will advance knee joint finite element models.

The morphology of the tibial footprint of the anterior cruciate ligament changes with ageing from oval/elliptical to C-shaped

PURPOSE

To further the current understanding of the modifications of the morphology of the ACL tibial footprint in healthy knees during the ageing process. The hypothesis is that there are differences in the morphology of the ACL tibial footprint between the cadavers of the young and elderly due to a degenerative physiological process that occurs over time.

METHODS

The tibial footprint of the ACL was dissected in 64 knee specimens of known gender and age. They were divided into four groups by age and gender, setting 50 years of age as the cut-off point. Three observers analyzed the tibial footprint dissections and the shape was described and classified.

RESULTS

The knees from the cadavers of males older than 50 years of age presented a "C" morphology in 85% of the cases. In the group of males aged less than 50 years, an oval/elliptical morphology was found in 85.7% of the cases. In the group of women over 50 years-old, the "C" morphology was observed in 82.3% of the cases. In women under the age of 50, the oval/elliptical morphology was found in 84.6% of the cases. A significant difference was observed between the prevalence rates of the morphologies of the younger and older groups (p < 0.001 for both genders). However, no differences were observed between males and females of the same age group (n.s.).

CONCLUSIONS

The morphology of the tibial footprint of the ACL presents significant variations with ageing. It can go from an oval/elliptical shape to a "C" shaped morphology. The results of this work make for an advance in the individualization of ACL reconstruction based on the age and the specific morphology of the tibial footprint.

The assessment of instability in the osteoarthritic knee

Patient-reported instability is a common complaint amongst those with knee arthritis.

Much research has examined the assessment of self-reported instability in the knee; however, no definitive quantitative measure of instability has been developed.

This review focuses on the current literature investigating the nature of self-reported instability in the arthritic knee and discusses the possibilities of further investigation.

Cite this article: EFORT Open Rev 2019;4:70-76. DOI: 10.1302/2058-5241.4.170079

Variation in the shape of the tibial insertion site of the anterior cruciate ligament: classification is required

PURPOSE

To propose a classification system for the shape of the tibial insertion site (TIS) of the anterior cruciate ligament (ACL) and to demonstrate the intra- and inter-rater agreement of this system. Due to variation in shape and size, different surgical approaches may be feasible to improve reconstruction of the TIS.

METHODS

One hundred patients with a mean age of 26 ± 11 years were included. The ACL was cut arthroscopically at the base of the tibial insertion site. Arthroscopic images were taken from the lateral and medial portal. Images were de-identified and duplicated. Two blinded observers classified the tibial insertion site according to a classification system.

RESULTS

The tibial insertion site was classified as type I (elliptical) in 51 knees (51 %), type II (triangular) in 33 knees (33 %) and type III (C-shaped) in 16 knees (16 %). There was good agreement between raters when viewing the insertion site from the lateral portal (κ = 0.65) as well as from the medial portal (κ = 0.66). Intra-rater reliability was good to excellent. Agreement in the description of the insertion site between the medial and lateral portals was good for rater 1 and good for rater 2 (κ = 0.74 and 0.77, respectively).

CONCLUSION

There is variation in the shape of the ACL TIS. The classification system is a repeatable and reliable tool to summarize the shape of the TIS using three common patterns. For clinical relevance, different shapes may require different types of reconstruction to ensure proper footprint restoration. Consideration of the individual TIS shape is required to prevent iatrogenic damage of adjacent structures like the menisci.

LEVEL OF EVIDENCE

III.

The utility of bicruciate-retaining total knee arthroplasty

Background

We describe the features of modern and historical bicruciate-retaining (BCR) total knee arthroplasty (TKA) implants compared with other TKA implant designs, reviewing kinematics, proprioception, operative technique, and clinical results.

Methods

We performed a review based on PubMed, Embase, CINAHL Plus, and Cochrane databases from January 1990 to April 2016 using combinations of the following keywords: “bicruciate-retaining arthroplasty,” “bicruciate-retaining total knee arthroplasty,” “bicruciate-retaining TKA,” “kinematics,” “knee kinematics,” and “TKA kinematics.”

Results

Four studies have supported the notion that preservation of both cruciate ligaments in TKA preserves more “normal” knee kinematics. BCR implants provide greater proprioceptive performance when compared with posterior cruciate-retaining (CR) TKA implants. However, the operative implantation is more challenging with BCR TKAs, requiring the surgeon to take additional precautions. Overall, there did not seem to be a significant difference in short-term clinical outcomes between the BCR and CR implants.

Conclusions

The utility of BCR TKA is still debatable. The literature has not shown clear indications and guidelines for the value and use of this implant. Although kinematics have been shown to mirror the native knee more closely, the clinical outcomes of BCR vs CR TKAs do not differ significantly. Moreover, additional care must be taken when inserting a BCR implant. The anterior cruciate ligament exploration and preservation is more challenging and certain preparation and precautions must take place. Overall, we have not found that BCR implants are significantly superior to CR implants with regards to short term clinical outcomes despite the BCR TKA having improved kinematics and proprioception.

Macroscopic evaluation of the anterior cruciate ligament in osteoarthritic patients undergoing total knee arthroplasty

BACKGROUND

Sacrifice of the anterior cruciate ligament (ACL) is currently common practice during total knee arthroplasty (TKA). However, patients who receive an ACL-retaining TKA maintain more normal knee kinematic patterns than those without an ACL. Additionally, satisfactory survival and function more than 20 years after bicruciate-retaining TKA has recently been reported. The purpose of this study was to compare the percentage of knees with a visually intact ACL prior to TKA surgery with previously reported values.

METHODS

A total of 247 knees (216 consecutive patients) that underwent TKA were retrospectively evaluated. The preoperative diagnosis for all patients was primary OA. The macroscopic appearance of the ACL at the time of surgery was retrospectively assessed using routinely recorded digital photographs and classified as normal, moderately damaged (fissured), or completely ruptured. Both normal and moderately damaged ACLs were defined as intact.

RESULTS

Ninety-four percent (233/247) of the knees had an intact ACL (normal or moderately damaged). This value is higher than that found in previous reports.

CONCLUSIONS

Our results show more candidates for bicruciate ligament-retaining TKA surgery than reported previously. This suggests that improved techniques for bicruciate-retaining TKA would be clinically useful and could benefit a large number of patients.

Anterior cruciate ligament insertion after partial tear: histological changes and chondrocyte turnover

PURPOSE

The purpose of this study was to clarify the effects of partial resection on the glycosaminoglycan (GAG) layer thicknesses and chondrocyte turnover (apoptosis and cell proliferation) between uncalcified fibrocartilage (UF) and calcified fibrocartilage (CF) layers in an anterior cruciate ligament (ACL) insertion.

METHODS

Twenty male Japanese white rabbits were evaluated. The anteromedial bundle of the ACL substance was resected in the right knee. The posterolateral bundle was left intact. Five rabbits were evaluated at 1, 2, 4, and 8 weeks after surgery, respectively.

RESULTS

The apoptosis rates in the UF and CF layers were significantly lower in the posterolateral area than those in the anteromedial area at 1 and 2 weeks, respectively. The cell proliferation rates in the UF and CF layers were significantly higher in the posterolateral area than those in the anteromedial area at 2 and 4 weeks, respectively. The GAG layer thicknesses in the UF and CF layers were higher in the posterolateral area than those in the anteromedial area at 1-8 and 2-8 weeks, respectively. The GAG layer thicknesses in the UF and CF layers in the posterolateral area peaked at 2 and 4 weeks, respectively. However, the thicknesses in the two layers in the posterolateral area gradually decreased until 8 weeks.

CONCLUSION

The GAG layer thicknesses in the UF and CF layers in the remaining ligament area increased up to 4 weeks and gradually decreased until 8 weeks owing to an imbalance between chondrocyte apoptosis and proliferation. If the reactions in humans are similar to those observed in the rabbits, we consider that augmentation for ligament reconstruction and partial repair should be performed within at least 1 month after injury, before insertion degeneration occurs.