Knee Cartilage Repair: Surgical Techniques and Considerations

Knee Cartilage Repair: Surgical Techniques and Considerations

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Knee cartilage injuries, stemming from trauma or degeneration, can severely impact joint function. Surgical intervention is crucial when conservative treatments fail, aiming to repair or restore damaged cartilage and alleviate symptoms. This intervention is particularly important for individuals seeking to return to high-demand activities. Ultimately, surgery plays a vital role in addressing knee cartilage injuries, restoring function, and improving quality of life.

Arthroscopic Procedures

Arthroscopic procedures involve the insertion of an arthroscope into the knee joint to visualise and treat cartilage injuries. The primary purpose is to diagnose and address knee problems with minimal disruption to surrounding tissues. By accessing the knee through small incisions, surgeons can precisely assess and treat cartilage damage, improving patient outcomes and reducing recovery time compared to traditional open surgery.

Types of Arthroscopic Procedures for Knee Cartilage Injuries

By providing direct visualisation of the joint and precise surgical intervention, arthroscopy has become a cornerstone of modern orthopaedic surgery for knee cartilage injuries. Some arthroscopic procedures for knee cartilage injuries include:

• Debridement: Debridement involves the removal of damaged or degenerated cartilage and tissue fragments from the knee joint. This procedure aims to alleviate pain and improve joint function by eliminating loose or roughened cartilage surfaces that can cause friction and inflammation.


• Microfracture: Microfracture is a technique used to stimulate the formation of new cartilage in areas of damaged cartilage. Small holes are created in the bone beneath the damaged cartilage, allowing bone marrow cells to migrate to the surface and form a blood clot. This clot serves as a scaffold for the growth of new cartilage tissue, promoting healing and repair.


• Chondroplasty: Chondroplasty involves smoothing or reshaping the surface of damaged cartilage in the knee joint. Using specialised surgical instruments inserted through the arthroscope, surgeons remove rough or irregular cartilage surfaces, reducing friction and improving joint function.


• Synovectomy: Synovectomy is the surgical removal of inflamed or hypertrophic synovial tissue lining the knee joint. This procedure aims to reduce inflammation and alleviate pain associated with conditions such as rheumatoid arthritis or synovitis.

Surgical Technique and Approach

Arthroscopic procedures are performed under general or regional anaesthesia, with the patient positioned on the operating table. Small incisions are made around the knee joint to insert the arthroscope and surgical instruments. The surgeon navigates the arthroscope through the joint, visualising the cartilage and surrounding structures on a monitor. 

Depending on the specific procedure, damaged cartilage may be removed, smoothed, or stimulated to promote healing. Once the procedure is complete, the incisions are closed, and the knee is typically immobilised with a brace or bandage.

Cartilage Repair Techniques

Cartilage repair techniques represent a crucial aspect of modern orthopaedic surgery for addressing knee cartilage injuries. These techniques aim to restore damaged cartilage, alleviate symptoms, and improve joint function, ultimately promoting long-term joint health and mobility. 

Autologous Chondrocyte Implantation (ACI)

Autologous chondrocyte implantation involves harvesting healthy cartilage cells (chondrocytes) from the patient's own body, typically from a non-weight-bearing area of the knee. These cells are then cultured and expanded in a laboratory before being implanted into the damaged area of the knee cartilage. ACI aims to promote the growth of new cartilage tissue and restore the structural integrity of the joint, offering a promising solution for repairing focal cartilage defects.

Osteochondral Autograft Transplantation (OAT)

Osteochondral autograft transplantation, also known as mosaicplasty, involves harvesting small cylindrical plugs of healthy cartilage and bone from a non-weight-bearing area of the knee and transplanting them into the damaged area. This technique aims to replace the damaged cartilage with healthy tissue, restoring the smooth surface of the joint and improving joint function. OAT is particularly effective for treating small to medium-sized cartilage defects in the knee.

Osteochondral Allograft Transplantation

Osteochondral allograft transplantation involves transplanting cartilage and bone tissue from a donor cadaveric source into the damaged area of the knee. This technique is used to treat larger or more complex cartilage defects that cannot be adequately addressed with autologous techniques. Osteochondral allograft transplantation offers the advantage of providing a large and structurally intact graft, facilitating the repair of extensive cartilage damage.

Matrix-induced Autologous Chondrocyte Implantation (MACI)

Matrix-induced autologous chondrocyte implantation is a variation of ACI that involves seeding cultured chondrocytes onto a biocompatible scaffold before implantation into the damaged area of the knee cartilage. The scaffold provides structural support for the newly implanted cells and promotes the formation of new cartilage tissue. MACI offers the advantage of improved cell retention and distribution within the defect site, enhancing the success rate of cartilage repair.

Scaffold-based Techniques

Scaffold-based techniques involve the use of biocompatible scaffolds to support and promote the growth of new cartilage tissue within the damaged area of the knee. These scaffolds may be composed of natural materials such as collagen or synthetic polymers. Scaffold-based techniques provide a framework for cell attachment, proliferation, and differentiation, facilitating the repair of cartilage defects and improving joint function.

Rehabilitation Considerations Post-Surgery

Post-surgical rehabilitation typically involves a structured programme of physiotherapy, including exercises to improve range of motion, strengthen the surrounding muscles, and enhance joint stability. Rehabilitation protocols may vary depending on the specific surgical technique used and the extent of the cartilage damage. Close collaboration between the patient, surgeon, and physiotherapist is essential to ensure a successful recovery and return to normal activities.

Comparison of Surgical Options

When considering surgical interventions for knee cartilage injuries, it's essential to weigh the effectiveness, patient suitability, and advantages and limitations of each technique. 

Effectiveness and Outcomes

Assessing the effectiveness of surgical options involves evaluating factors such as pain relief, functional improvement, and long-term outcomes. While arthroscopic procedures like debridement and microfracture may offer symptomatic relief and promote healing in select cases of focal cartilage defects, more extensive injuries may require advanced techniques such as autologous chondrocyte implantation (ACI) or osteochondral transplantation for optimal outcomes.

Patient Selection Criteria

Patient selection criteria play a crucial role in determining the most appropriate surgical option for knee cartilage injuries. Factors such as the size, location, and severity of the cartilage defect, as well as the patient's age, activity level, and overall health, must be carefully considered. For instance, younger patients with isolated focal defects may benefit from ACI or osteochondral transplantation, while older individuals with more extensive damage may require less invasive options such as arthroscopic debridement.

Advantages and Limitations of Each Technique

Each surgical technique for knee cartilage repair comes with its own set of advantages and limitations. Arthroscopic procedures offer the advantage of minimally invasive treatment with shorter recovery times but may be limited in their ability to address larger or more complex cartilage defects. 

Autologous techniques like ACI and osteochondral transplantation provide the advantage of using the patient's own tissue. This reduces the risk of rejection but may require longer recovery periods and have higher associated costs. Allograft transplantation offers the advantage of using donor tissue to address extensive cartilage defects but may carry a risk of disease transmission and graft rejection.

In Summary

Surgical options for knee cartilage injuries encompass a range of techniques aimed at restoring joint function and alleviating symptoms. From minimally invasive arthroscopic procedures to advanced autologous and allograft transplantation techniques, each approach offers unique benefits and considerations. 

When making treatment decisions, factors such as the extent of cartilage damage, patient demographics, and desired outcomes must be carefully considered. Importantly, individualised care and tailored rehabilitation plans play a crucial role in optimising treatment outcomes and promoting long-term joint health. By combining surgical expertise with personalised rehabilitation strategies, orthopaedic surgeons can effectively address knee cartilage injuries and improve the quality of life for affected individuals.

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