Cartilage Injury

What is cartilage?

Cartilage is a connective tissue that lies within the joint surfaces of certain joints such as the knee joint. Articular cartilage is a layer of soft tissue covering the ends of long bones that form the synovial joints. It is made up of hyaline cartilage, which is a tough yet flexible tissue. Synovial joints are highly mobile joints. The cartilage acts as a shock absorber for these joints. It allows free movement by reducing friction between the joint surfaces. The cartilage also helps in force transmission across the joint surfaces.

Dynamic loading and regular activity are essential for healthy cartilage. Injury to the cartilage results in increased friction between the joint surfaces. Loss of the lubricating surfaces causes erosion of joint surfaces. Cartilage injury can occur at the shoulder, elbow, hip or ankle joints. However the knee joint is most susceptible to cartilage injury as it is the major weight bearing joint. This can act as a precursor to osteoarthritis in the knee.

Damage to the knee cartilage is a relatively common complaint. When people discuss cartilage damage they are generally referring to the meniscus that sits inside the knee joint itself. When the meniscus of the knee is injured there may be an associated pop or click in the knee joint. This may be associated with knee pain going up a stairs or ‘giving way’ of the knee at points where increase stress is placed on the injured tissue.

Causes of Knee Meniscus Injury

The knee cartilage (meniscus) can be injured through a significant knee trauma or can come about through repeated mild trauma over several years. The mechanism of injury commonly involves a rotational movement at the knee with the foot planted on the ground. Any sports or activities involving repeated rotation at the knee can predispose an individual to cartilage injury, thus the incidence of this injury is high in field sports such as soccer.

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Articular cartilage: Special features

The articular cartilage differs significantly from other soft tissues such as ligaments & tendons.

• Structure:  The articular cartilage is divided into different zones. Cells in the outermost zone provide resistance to translational forces on the cartilage. The collagen fibres in the middle zone and the proteoglycans in the deep zone resist the compressive forces. Collagen also imparts elasticity to the cartilage. The deepest (calcified) zone anchors the cartilage to the underlying bone.

 

• Composition:  The articular cartilage is made up of a gel like matrix that is composed of chondrocytes, water, collagen, proteoglycans and other smaller cells. Chondrocytes are responsible for the formation and maintenance of this matrix. Water constitutes around 80% of the matrix giving it the gel-like consistency. The tough and elastic collagen fibres make up 60% of the cellular content of the cartilage.

 

• Nutrition: Unlike other soft tissue structures, the articular cartilage has a poor blood and lymphatic supply. This means the normal rules of inflammation and healing do not apply. This is a major reason for poor intrinsic healing capacity of the cartilage. The cartilage derives its nutrition through a process of diffusion. The nutrients from the synovial fluid diffuse in through the outer layers of the cartilage.

 

• Nerves: The cartilage also does not have a nerve supply. Thus, cartilage itself is not the source of pain. However, a significant loss of cartilage can expose the underlying bone. When this exposed bone surface rubs against the adjoining bone, it may cause pain. Surrounding structures like torn ligaments and menisci can also be the generators of pain.

 

• Injury: Articular cartilage injury is seldom isolated. It usually occurs as a side effect of ligament or meniscal injuries. These injuries change the walking or running patterns thus altering the weight transmission through the joints. Unequal loads cause damage to the articular cartilage.

 

• Repair: Under normal stresses as with walking and jogging, the cyclic compressive loads that occur while walking stimulates the chondrocytes to produce more cartilage matrix. There is a delicate balance between the breakdown of old matrix and synthesis of a new one. Increased stresses over a prolonged period can disturb this delicate balance and trigger degeneration. Since the cartilage does not have a blood supply, it is unable to repair itself. The chondrocyte replication rate is very slow. Thus, when a fall or a sporting injury damages the cartilage, its ability to heal is limited. Damage to one part of the cartilage is often propagated to adjacent areas.

 

Symptoms of articular cartilage injury

• Pain, swelling and tenderness around the affected joint.
• Reduced mobility in the affected joint
• ‘Locking’ in certain directions due to loose pieces of cartilage floating in the joint
• Pain on weight bearing

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Risk of articular cartilage injury

• Contact sports are a risk factor for damage to the articular cartilage due to their high impact nature. 32% of footballers suffer from progressive cartilage damage.
• Associated ligament or meniscus damage increases the risk of cartilage damage. Injury to the anterior cruciate ligament in particular is highly associated with future cartilage injury and arthritis.
• Accelerated wear and tear is seen in athletes who perform repeated twisting movements over prolonged periods. Increasing the intensity of activity up to a certain threshold increases cartilage thickness and strength. Stresses beyond this point accelerate cartilage breakdown.
• Obesity is linked to early breakdown of the cartilage. BMI (body mass index) over 30 increases the risk of injury.
• Extended periods of inactivity results in poor cartilage nutrition and breakdown. Regular activity stimulates the chondrocytes to produce healthy cartilage.
• Improper alignment in the legs like knocked knees or bow knees also trigger cartilage disruption due to abnormal forces being applied across the cartilage surface

 

How to diagnose a cartilage injury?

MRI imaging can help to detect articular damage. The damaged region will have a different density as compared to  healthy tissue.

Arthroscopy is a reliable method to gauge the extent of damage. The technique uses a camera to explore the interior of the joint.

Can Physiotherapy help with an articular cartilage injury?

Though, on occasion, surgery is the best option for high-level athletes, conservative management through physiotherapy is generally  considered the primary option in non-sporting populations. Even for athletes opting for surgery, rigorous pre and postoperative physiotherapy is necessary to facilitate a return to sports. 

Physiotherapy treatment can help minimise the risk factors that lead to cartilage injury. Switching to low impact activities such as swimming and static cycling can help a person to reduce weight. They also maintain cardiovascular fitness. Loss of weight can help arrest the spread of cartilage damage and alleviate pain to a large extent.

An experienced sports physiotherapist can identify the postural and biomechanical faults in standing, walking, and running. Correcting alignment issues and technique faults help to reduce pain and swelling.

A good exercise program after a cartilage repair includes a specific stretching and strengthening based on your specific deficiencies. Adequate strength of the muscles surrounding the joint is vital to support the joint during daily and sporting activities and for preventing damage to the joint cartilage. Strong muscles effectively offset the loads on the joints. This eases the pressure on the joint itself. For example, quadriceps strengthening is highly effective in reducing knee pain. Core strength has also shown to affect mechanics around the knee joint.

Weight transmission through the knee joint can be improved by performing hamstring and calf muscle stretching. Flexibility in these muscles ensures a proper walking and running pattern.

Once the normal joint range is achieved and walking is painless, more complex exercises are introduced. This involves balance and coordination exercises. This is followed by eccentric exercises. Eccentric exercises are movements involving muscle contraction simultaneously while the muscle is lengthening.

Gradually your therapist may add sports specific drills such as plyometrics (explosive exercises), running, and cutting movements.

Normally it takes around 6-18 months to return to competitive football after an articular cartilage repair. The rehab should be continued for at least 2 years after surgery. The main challenge is avoiding overtraining as that may damage the repair.

Physiotherapy Treatment of Knee Meniscus Injury

Although surgery is an option for more severe cartilage (meniscus) injuries, generally most people can mange their symptoms via physiotherapy interventions and an exercise programme prior to taking this option. In high level athletes, surgery may be warranted at an earlier stage for cartilage injury repair.

Abnormalities in movement patterns can predispose to cartilage injury and these patterns should be addressed in order to prevent further damage and re-injury. A period of rest from the aggravating activity is usually warranted and the more comprehensive the rehabilitation process the less likely the condition is to progress rapidly.

Articular cartilage: Surgical treatment options

The following are keyhole surgeries performed using an arthroscope. A thin tube with a camera attached at the end is inserted through the joint and micro instruments are inserted in an attempt to carry out the cartilage repair. The effectiveness of these procedures has been strongly questioned in the published literature.

1. Lavage and debridement: The procedure involves removal of loose pieces of cartilage and trimming uneven edges of the damaged part.
2. Microfracture: Small holes are drilled in the bone underlying the injured cartilage. This allows the bone marrow cells to come to the surface. Bone marrow cells are basic cells that can differentiate into any type of cell. In this case the marrow cells take up the function of chondrocytes and begin to produce new cartilage. Younger athletes respond better to this procedure if performed within 12 months of injury.
3. Mosaicplasty: Small pieces from healthy part of the cartilage are removed and plugged into the damaged areas. This has been successful with as many as 93% of the athletes returning to competitive sports.
4. Osteotomy: A wedge from the joint surface or shin bone is removed in order to correct any alignment faults.This helps to even out the pressure on the cartilage.
5. Joint replacement: This is done in case of severe cartilage damage. The diseased joint is replaced by an artificial metallic one.

 

Treatment options on the horizon:

1. Injecting platelet rich plasma: High-level clinical trials are on to ascertain the effectiveness of this technique. In this procedure, specific growth factors and proteins are introduced with the aim of speeding up cell replication and cartilage formation. The research is inconclusive on this technique
2. Advanced microfracture technique: Through the use of tissue engineering, scientists are working on improving the replication and cartilage production capacity of the basic bone marrow cells. (Mesenchymal cells)
3. Neocartilage implantation: A piece of healthy cartilage is removed and grown in the lab and implanted in the damaged areas.
4. Allograft implantation: Chondrocytes of younger adults are more active. Removing small pieces from a juvenile donor and shaping it to fit the defect in an adult recipient is the mainstay of this procedure. The piece is fixed with special fibrin glue. It’s a minimally invasive procedure.

 

To find out more, contact Naas Physio Clinic on:
(083) 1960344

or email us at info@physioclinic.ie