Ankle distraction is a new treatment modality for ankle arthritis that is particularly useful in young adults. In this age group if the conservative treatment fails the 2 standard treatment options of ankle fusion and ankle replacement are both not ideal.
The distraction depends on stretching the soft-tissues surrounding the ankle to improve the ankle joint space. The technique utilises a circular frame called the Ilizarov Frame that is fixed around the foot and leg for 2 to 3 months.
The concept of “Joint Distraction”
The concept of gradual distraction is referred to as “distraction histogenesis.” This concept, developed in Russia many years ago, involves applying gradual constant tension to tissues using a circular external fixator. This causes the tissues to lengthen over a period.
The technique was used to lengthen limbs and correct deformities, with a vast spectrum of applications in different parts of the body.
Ankle Joint Distraction is a relatively new technique that is still being investigated to fully understand its capabilities. The exact mechanism that causes improvement in the patient’s symptoms is still not fully understood.
The technique involves applying an external frame (called the Ilizarov Frame) across the ankle joint. This frame is used to gradually distract the joint. The gradual distraction offloads the cartilage covering the bone ends and stretches the tight surrounding soft tissues allowing the joint to be less stiff. The gradual distraction causes the tissues of the Achilles tendon and the soft tissues at the back of the ankle to lengthen, improving the joint flexibility.
Most of the description of this technique refer to a static frame usually a Taylor Spatial Frame (TSF) to achieve the distraction. The technique that we use however utilise a dynamic frame that allows the patient to keep moving their ankle during the distraction process. The results have shown that this technique yields much better outcome.
The patient is allowed full weight-bearing all through the frame time. The frame stays on the ankle for a period of 2 to 3 months. The distraction happens by moving special nuts to lengthen the connecting rods between the foot ring and the leg frame. Any associated deformity can also be corrected simultaneously.
Results of Ankle Joint Distraction in the Literature
In a prospective study of 17 ankles with a minimum follow-up of 2 years *, significant improvement in the physical, functional & pain scores was noticed. Seventy five percent of the patients noticed an improvement in the range of movement and 50% showed significant improvement of the joint space on their final x-rays.
In another randomised controlled trial of 40 ankles comparing dynamic & static distraction **, both groups showed an overall improvement of all the outcome scores. There was more continued improvement in the dynamic group and more improvement in pain scores in the dynamic group.
In another prospective study of 57 ankles with a mean follow-up of 7 years ***, there was statistically significant better clinical outcome for the patients who underwent distraction compared to those who had arthroscopic debridement of the ankle alone.
In Edinburgh, we have results comparable to these studies with a marked improvement in the pain and good restoration of the joint space. With a shift to dynamic distraction we also noticed improvement in our results.
References
* Van Valburg 1999 , ** Saltzman 2011 , *** Marijnissen 2002, 2003