>Cartilage Injuries of the Ankle
The normal ankle joint, like most joints in the body, is lined by hyaline articular cartilage. This is a firm smooth surface which allows the two surfaces of the joint to glide smoothly together during movement. Any damage to this articular surface can result in chondral injuries.
Mechanism of Injury
The ankle is commonly involved in work-related injuries. The articular or chondral surface is particularly prone to inversion injuries. This is the typical ankle “sprain” where the foot and ankle turn “inwards”. Other types of ankle injuries can also damage the joint surface. This often occurs in work-related settings such as walking on uneven surfaces.
Chondral injuries can vary in size, location and also the depth of the cartilage surface involved. There may only be a partial thickness injury where the most superficial layers of cartilage cells may are involved, or the full thickness of cartilage down to the underlying bone may be affected. Symptoms vary but if the chondral injury is large enough it can lead to acute pain, swelling and stiffness. In addition if a fragment of the torn cartilage becomes loose and separates, it can be caught between the ankle joint surfaces. This can result in the ankle getting stuck or “locked” with certain activities resulting in severe pain and inability to walk. This often results in great difficulty returning to normal work duties.
As the cartilage lining the ankle joint has only a very limited blood supply and little potential for regeneration in an adult, injuries to the joint surface do not generally heal well. If not appropriately treated the problem is of ongoing pain and swelling which will impede rehabilitation and fitness for work.
Following an acute work related ankle injury, the investigations ordered depend on the clinical findings on examination of the ankle. It is reasonable to have an Xray performed to exclude any fractures but this does not actually demonstrate subtle injuries to the cartilage surface given that it is generally not mineralized and thus does not show up on an Xray. As such this may require a special MRI scan to define a cartilage injury.
It is generally reasonable to attempt physical rehabilitation in the first instance to accelerate fitness for work. A combination of anti-inflammatory medication and bracing or strapping of the ankle can help. Physiotherapy is also useful to regain strength and movement through the ankle with specific exercises. Other modalities such as ultrasound treatment can also be beneficial. In addition cartilage injuries are often associated with inflammation of the lining of the ankle joint or “synovitis”. If this is severe a cortisone injection directly into the ankle joint may help.
While most cartilage injuries of the ankle respond to this treatment, a small proportion of patients have ongoing symptoms. This is usually due to a large full thickness injury or a fragment of loose cartilage which becomes entrapped within the joint surfaces. In such cases surgical intervention may be required. The technology now exists to perform this through arthroscopic or “keyhole” surgery. This is generally performed under a general anaesthetic with the patient asleep.
The injury to the cartilage is assessed and any loose or unstable cartilage fragments are removed to create a smooth surface. If the injury involves the full thickness of the cartilage surface and bare bone is visible, this does not have the potential to heal with normal cartilage. As such the bone is drilled to stimulate healing with a scar tissue response or fibrocartilage. While this does not fully replicate the mechanical properties of the normal hyaline cartilage lining the ankle joint, in at least 80% of patients there is a significant improvement of symptoms.
While the normal hyaline cartilage lining the ankle does not naturally regenerate in an adult, there is the potential in a select group of patients to attempt a cartilage graft. This is still an experimental procedure in which the long term success rates are as yet unknown. At this stage few patients have symptoms bad enough or meet the strict criteria to have this surgery.
Arthroscopic surgery is generally performed as an inpatient case. Depending on the specific problems with the ankle most patients will have a cast or brace on the ankle following surgery and will be restricting their weight bearing with crutches. Sufficient pain relief is organized and rehabilitation commences generally in a further two weeks once the wounds have adequately healed. This primarily involves range of movement exercises and strengthening of the muscles, and a rapid return to full weight bearing. A physiotherapist can be helpful in assisting with this.
Depending on the degree of the cartilage injury and amount of surgery required, most patients are comfortably weight bearing and walking without crutches approximately two weeks following surgery. A brace may be required and at this stage fitness for work would be reasonable to consider for office based duties and some manual jobs. Physical rehabilitation increases at this stage and can include hydrotherapy and further muscle strengthening exercise. In general fitness for work for heavy manual labour can be considered between four to six weeks following surgery, when a brace is usually no longer required.
Following arthroscopic surgery, the patient should avoid prolonged standing and weight bearing for the first two weeks. Thereafter work-related activity levels can be increased and by six weeks following surgery, few work restrictions generally apply.
In general most patients recover well from work-related articular cartilage injuries of the ankle if they are appropriately treated. There is a theoretical concern of potential arthritic changes occurring after loss of part of the cartilage surface especially as the fibrocartilage scar that forms does not have the same mechanical properties as normal hyaline cartilage. However in general only the abnormal and torn part of the cartilage is removed leaving as much of the normal cartilage intact as possible, and the majority of patients will have a good outcome in the long term. The outcome following removal of loose cartilage is also far better than leaving a fragment locked between the joint surfaces.
Disclaimer: Please note that the information in this article is intended as only a general guide to cartilage injuries of the ankle. Every patient’s clinical situation will differ and treatment is modified depending on the specific problems and needs of each patient.
Dr. Rezah Salleh
Suite 217 Saint John Of God Subiaco Clinic
25 McCourt Street
Subiaco WA 6008
Phone: (08) 9382 9102
Fax: (08)9382 9104