Surgical treatment of pathological posterior medial meniscal extrusion: A biomechanical study comparing centralization techniques.

The meniscus is a fibrocartilage structure of the knee. It helps to distribute load and act as a shock absorber. When you tear the attachment site of the meniscus i.e. the root, this can have detrimental effects. This includes the meniscus moving out of the joint (called meniscal extrusion) leading to the tibia and femur rubbing against each other and subsequently arthritis.

Knee surgeons tend to fix the meniscal root, so that we can delay or even prevent this from happening. However, despite this, research has found that the meniscus can still extrude, leading to the detrimental pathology described.

Over the last ten years, surgeons have come up with newer techniques where they add in a procedure in addition to fixing the root to prevent this from happening. This procedure is called centralization, where the meniscus is held down at its periphery, and has nowhere to move.

There are many different types of centralization described in the literature. One includes the insertion of suture anchors, whilst the other pulling the sutures down a tunnel within the tibial bone and tied over a ‘button’. However, they have never been compared to one another, and so we are unsure which is the best to perform and vital for knee surgeons to be trained in.

The main aims and objectives of the research study.

We aim to compare the commonest centralization techniques biomechanically on animal knee joints. Our goal is to see which technique is the most effective in keeping both the meniscus rooted down at its periphery and the kinematics of the knee as close to a healthy one.

This will then lead to future studies where we can examine these on patients and monitor their progress.

How this research is going to help address MSK health.

Much of the research in centralization involves the proposal of surgical techniques, with the current clinical body of literature devoid of long-term studies with high methodological quality.

Despite its evolving practice, there is no standardized technique. It is imperative one explores which of the commonest centralization procedures produces the best results in bringing the knee kinematics as close to normal. Consequently, this will reduce tibiofemoral contact pressures, cartilage degeneration and delay/prevent knee osteoarthritis. By fulfilling this gap in the literature. can one subsequently perform novel clinical trials to evaluate patient outcomes using the biomechanically optimum centralization technique in combination with root repair to fully determine its efficacy. This would be of immense benefit to surgeons as it would enable the provision of alternative treatment options to salvage the native joint.

The main research methods, or datasets being used.

We aim to compare 5 testing situations in porcine knee joints. These are:

1. Normal meniscus
2. Torn meniscal root
3. Meniscal root repair
4. Meniscal root repair + transtibial stitch centralization
5. Meniscal root repair + suture anchor centralization

The main outcomes we are looking at are:

1. loading profile within the knee (tibiofemoral contact mechanics) and whether the repair brings it close to that of a normal meniscus
2. The degree of extrusion with the different techniques and which one brings it closer to the native state

Loading profile is being measured with pressure sensors which are then calibrated on a mathematic software. Extrusion is measured with sophisticated markers, also calibrated on software

Research results generated.

Meniscal root repair + transtibial stitch restores the loading profile and extrusion closest to the native state compared to root repair alone

Next steps of this research project.

 To complete the testing with anchor centralization and whether this improves/worsens/creates no difference to the outcomes when compared to transtibial stitch

Publications and presentations related to this fellowship.

 Three systematic reviews generated on this topic, providing both a background basis, and improvements in research methodology in laboratory testing. All currently under review in PubMed ID Journals.

Impact of this Orthopaedic Research UK fellowship on your research and career

“Much of soft tissue disease in musculoskeletal surgery is underpinned by alterations in the kinematics of a normal joint. Its biomechanical restoration provides a pathway to reducing the rate of advanced disease.

As a prospective knee surgeon with a strong academic interest, I would like to ensure patients are able to make the most out of their native joints for as long as possible (and with satisfaction) prior to the introduction of ‘implanted’ materials i.e. arthroplasty and transplantation, all of which have their own potential pitfalls.

If the current research identifies an optimum centralization technique to restore native joint biomechanics to delay OA, then further in vivo clinical trials will be undertaken to determine its true clinical efficacy. Potentially this may improve patient reported outcome measures, reduce the conversion to total knee arthroplasties and ultimately decrease healthcare costs.”

Influence of research project on policy, practice or patients

The key objective of the study is to encourage breakthrough research to reduce the burden of poor musculoskeletal health in the population. Pioneering new treatments can delay the pathological sequelae of events that can occur with aging, trauma and disability to the knee. If the biomechanical study on centralization proves to show one technique to be superior, then this will be translated to clinical studies. If subsequently proven to delay/prevent knee osteoarthritis from extrusion, then this will prove beneficial in reducing the pain and immobility patients may suffer, whilst improving their physical and psychological well-being. Furthermore, this can reduce the economic burden on the NHS, particularly in number of outpatient clinics, physiotherapy sessions and need for TKAs in patients whose progression has stagnated. Ultimately, the release of financial constraints would provide the UK healthcare system the potential for funding further treatment options, creating a positive impact on the national population.

Researcher: Khalis Boksh

Supervisor(s): Prof. Duncan Shepherd, Dr. Daniel Espino and Mr. Tarek Boutefnouchet

University or Trust: University of Birmingham

Award stream: ORUK-RCSEd Research Fellowship

Award duration: 12 months

Amount rewarded: £60,000