Edited by Robert Leland, MD
Lateral ankle instability can be treated surgically, either with tightening of the existing ligaments (Brostrom procedure) or a lateral ligament reconstruction using a tendon graft (See Figure #1). While it is often the preference of the surgeon that determines which of these surgeries is performed, some general guidelines may influence the decision. A previous failure of an ankle ligament stabilization procedure may be an indication for a reconstruction using a tendon graft. Others feel that tendon graft reconstruction is best even for first time procedures, due to inherent weakness in the scar tissue left after damaging the ligaments. If gross laxity in the ankle exists particularly in a high activity demand patient, a free tendon graft reconstruction is preferable as the existing ligaments are often not amenable to providing enough ankle stability even if they are tightened.
Tendon reconstruction of the outside ankle ligaments involves stabilizing the stretched out dysfunctional ankle ligaments (anterior talofibular and calcaneofibular ligaments) by weaving a tendon graft through bones on the outside of the ankle where these ligaments normally attach(See Figure 1). This is performed using either: a nearby tendon; a tendon that has been harvested near the patients own knee joint (autograft tendon); or by using a tendon from a cadaver (allograft). The tendon graft is usually placed through the end of the fibula, the talar neck, and often the calcaneus (See Figure 1). There are a variety of ways to perform the reconstruction. In each case, the tendon is pulled tight and secured solidly to the bone so that the ankle joint will be stable when it is subject to an inversion force (See Figure 2). This procedure attempts to rebuild the lateral ligaments, and places the tendon graft as close to the original anatomic pathway of the lateral ligaments that were torn.
Recovery from a tendon reconstruction as treatment for ankle instability requires a period of immobilization usually on the order of 6 weeks. Depending on surgeon preference and patient compliance, either a hard cast or a removeable boot cast can be used. This allows the tendon-bone interface to consolidate. After approximately 6 weeks, the rehabilitation phase is started. The rehabilitation phase focuses on:
- Improving ankle motion
- Strengthening the muscles around the ankle
- Regaining ankle proprioception
- Improving gait
Some form of ankle bracing (ex. Ankle lacer) is often indicated for 6-12 months following surgery.
Potential Complications of the Surgery
There are some potential risks of surgery that are specific to lateral ligament reconstruction procedures. These include:
- Injury to the superficial peroneal or sural nerve: These nerves often run in the vicinity of the incision. The nerves are usually identified and not normally cut. However, even if the nerves are carefully retracted they may become damaged. Additionally, in the repair and healing process, this nerve can become scarred, leading to either decreased sensation over the top or outside of the foot or, in some cases, a painful burning sensation in this region. The majority of the time, this type of nerve injury recovers. If this type of neuritis occurs, fairly aggressive therapy to desensitize this area is required.
- Stretching out of the tendon reconstruction: Failure of the tendon reconstruction, either by stretching out or by the tendon graft pulling out of the bone, can occur. The tendon graft will stretch out when the tendon tissue is not strong enough to withstand the forces applied to it. The strength of the tendon graft is usually very strong when it is initially placed at the time of surgery. However, biologically the tendon graft actually weakens significantly in the months after surgery. This is because the tendon graft is usually without a blood supply when it is surgically positioned. The blood supply slowly gets re-established, and when this happens some of the tendon substance is reabsorbed, causing it to weaken. However, the tendon graft is usually quite strong to begin with so failure of the graft has not been a major problem. Even with a successful ankle ligament reconstruction, if a patient has a subsequent severe enough injury to their ankle, they may tear the tendon graft just like tearing a normal ligament.
- Another specific potential complication to tendon graft ligament reconstruction is irritation from hardware used to fix the graft to bone. This may require removal with a second surgery.
Patients undergoing the surgery are subject to the potential for the usual risks associated with surgery such as the risk of:
- Wound healing problems
- Nerve Injury
- Deep Vein Thrombosis (DVT)
- Pulmonary Embolism (PE)
- Some continued symptoms
This procedure is designed to effectively treat ankle instability. The pain that originates from other sources, such as the ankle joint itself, will not necessarily be addressed with this procedure.
If performed properly and for the correct indications, Ankle ligament reconstructions have a very high success rate and frequently allow patients to return to their desired activity levels with a stable ankle.