I. Overview
Ankle sprains are common, but it is unfamiliar to talk about ankle instability, which is mostly triggered by ankle sprains. It has been reported that after ankle sprains, the reoccurrence of sprains varies among different populations, up to 30-70%. Most acute sprains can be satisfactorily recovered after non-surgical treatment, but 20-40% of acute sprains gradually become progressive chronic ankle instability. Therefore, it is necessary for patients with ankle sprains to understand the relevant knowledge, and active cooperation with treatment is the key to success.
Classification of instability after ankle sprain.
1.Acute ankle instability;
2.Chronic ankle instability: including
①Functional instability and
② mechanical instability. Severe ankle sprains can manifest as acute ankle instability and later as mechanical instability of the ankle joint. Mild ankle sprains that are not treated properly can easily lead to repeated sprains and manifest as functional instability of the ankle joint.
Ankle sprains primarily damage the anterior talofibular ligament and the calcaneofibular ligament, which are key to stabilizing the lateral aspect of the ankle, and the sprain can elongate the ligament in mild cases or tear it in severe cases. Laxity of the anterior talofibular ligament causes excessive anterior displacement of the talus, and laxity of the heel-fibular ligament causes an increase in the tilt angle of the talus. If the ligaments heal poorly, the stability of the maintained ankle joint is poor.
The frequency of complications following ankle sprains and the long-term symptoms of ankle instability are mostly related to the following.
(i) It is estimated that approximately 55% of patients with ankle sprains do not seek treatment from a physician or specialist;
②Severe ankle sprains are often underestimated and current treatment strategies for ankle sprains may be ineffective in preventing recurrent ankle sprains and long-term symptoms of ankle instability;
(iii) most ankle sprains are inadequately treated, often leading to recurrent ankle sprains and ankle instability; (iv) simple ankle sprains are not all the same, and physicians fail to fully recognize the complexity of ankle sprains. The current intervention, diagnosis, and treatment of ankle sprains, re-trains, and ankle instability remain challenging
II. Diagnosis of ankle instability
The clinical manifestations of ankle instability after ankle sprain: history of ankle sprain or repeated sprains, pain, swelling, joint agitation and fear of walking on the lateral side of the ankle, habitual “weak leg” or direct re-torsion, difficulty in walking on uneven ground, joint dysfunction, etc.
A variety of pathologies may occur in ankle sprains, including instability, soft tissue impingement, post-traumatic osteoarthritis, joint ligament injury, tarsal sinus syndrome, subtalar joint instability, peroneal tendon injury, or osteochondral injury to the apex of the talus. The clinical manifestations of these lesions are similar to ankle instability, and they all belong to the category of ankle pseudostability, which needs to be distinguished from the above-mentioned true ankle instability.
A holistic assessment of acute sprains and chronic instability of the ankle is important for treatment. Clinical physical examination includes evaluation of the knee and the entire foot and ankle, lower extremity alignment, foot and ankle mobility, pressure pain localization, ankle stability, and proprioceptive testing.
Direct ligament stability tests include: anterior drawer test, talus tilt test, and proprioceptive test. It is usually compared with the contralateral side to determine whether there is laxity.
Imaging: Standard weight-bearing ankle radiographs include anteroposterior and lateral views. This ensures that there are no major bony structural abnormalities and that associated injuries are ruled out. Stress-position x-rays are controversial and are not relied upon clinically for diagnosis.
Conventional MRI images can show ligamentous injuries, osteochondral injuries, and tendon tears in the ankle joint. MRI is required in patients with acute sprains with instability, repeated sprains, chronic ankle instability, and in cases of lawsuits. In addition, ankle sprains are often associated with impingement syndrome, tarsal sinus syndrome, etc. MR is helpful in identifying associated and underlying lesions.
Treatment of ankle instability
Persistent ankle instability leads to persistent treatment problems. Treatment includes non-surgical and surgical treatment
(i) Non-surgical treatment: It is the initial treatment for all ankle instability and is important for the diagnosis of pseudo-unstable ankle if the treatment causes an increase in pain. Mechanical support and planned rehabilitation exercises are the main non-surgical treatment methods. The duration of non-operative treatment is longer than that of the initial ankle sprain.
1. Rehabilitation exercises: mainly emphasize proprioceptive exercises, peroneal muscle response training and peroneal muscle strength training
2. Mechanical support: a method to enhance proprioception. Mild hindfoot malalignment can be corrected with orthopedic shoes or orthoses. Lateral wedge pads can be used for many patients with lateral instability. Stirrup-type braces can effectively resist pronation and valgus and are most commonly used.
(II) Surgical treatment.
1.Surgical indications
1)The patient’s symptoms persist after rigorous rehabilitation exercises and brace fixation.
2)The patient has received previous failed surgical treatment and it is likely that some static and dynamic stable structures have been removed.
2. Surgical modalities.
(1) Anatomic repair and strengthening surgery;
(2) Non-anatomic ligament reconstruction;
(3) anatomical ligament reconstruction. There are about 80 kinds of procedures.
(1) Anatomic repair and strengthening: anatomic repair of the injured anterior talofibular ligament and heel-fibular ligament.
(1) Anatomic repair (Figure 1): described by Brostrom in 1966. The procedure consists of identifying the elongated or injured anterior talofibular ligament and heel-fibular ligament, cutting them at the middle, constricting them, and then repairing them with a direct suture in the middle;
(ii) Anatomic repair as well as strengthening procedure (Figure 2): In 1980, Gould modified the Brostrom procedure by strengthening the direct repair, mainly by loosening the proximal end of the lateral aspect of the extensor support band and fixing it in front of the fibula, overlying the Brostrom surgical procedure;
(iii) Suture rivet direct suture reinforcement approach (Figure 3).
(2) Non-anatomic reconstruction of the ligament: using all or part of the short fibular muscle, a “bridle” is created on the lateral aspect of the ankle in different ways to restore stability of the ankle joint. The three most commonly used procedures are the Watson-Jones, Evans, and Chrisman-Snook procedures. These three procedures are now obsolete and will not be described.
(3) Anatomic reconstruction of the ligament (Figure 4): the tendon graft is passed through the distal fibular tunnel and into the anatomic stops of the anterior talofibular ligament and the heel-fibular ligament; the graft is secured to the lateral aspect of the heel bone and the lateral aspect of the talar neck with a squeeze screw.