Allograft tendon reconstruction of the anterior talofibular ligament and calcaneofibular Ligament in the treatment of chronic ankle instability

Numerous procedures for ATFL and CFL reconstruction have been reported with various successful rate. Sugimoto and colleagues [10] used a bone-patellar tendon graft to reconstruct the ATFL and CFL in 13 patients with chronic ankle instability. At mean follow-up of 26.5 months, the average talar tilt degree improved from 18.4° ± 5.5° preoperatively to 4.9° ± 2.6° postoperatively, and the average ADT decreased from 9.1 ± 2.6 mm preoperatively to 5.8 ± 1.6 mm postoperatively. According to the score devised by Good, six patients had a Grade III clinical condition and seven had a Grade IV condition preoperatively. After surgery, all patients had a grade I condition.

Coughlin and colleagues [11] reported another surgical technique using a free gracilis tendon transfer to anatomically reconstruct the ATFL and CFL. At a mean follow-up of 23 months, the outcomes of 24 of 28 patients were regarded as excellent and four of 28 as good, according to subjective self-assessment, pain scores, AOFAS, and KAFS. Talar tilt degree decreased from 13° preoperatively to 3° postoperatively, and the ADT decreased from 10 mm preoperatively to 5 mm postoperatively.

Pagenstert and colleagues [12] described their technique to anatomically reconstruct ATFL and CFL using a free plantaris tendon graft without screw fixation. At a mean follow-up of 3.5 years in 50 patients, the mean AOFAS was 97.9. In 39 cases (78%), the outcome was graded as excellent, and in 9 cases (18%), as good. The reconstruction addressed both ATFL and CFL in a double fashion with great attention to normal kinematics of the ankle.

In the present study, we report data consistent with the previously described literature. The functional scores improved significantly after compared with before surgery. The reconstruction technique used was similar to that described by Pagenstert and colleagues [12], in that the anterior talofibular ligament was reconstructed in a double fashion that respected the normal kinematics of anterior talofibular ligament. However, our technique is unique in that the calcaneofibular ligament was reconstructed with a single tendon graft with an interference screw to fix the insertion. We believe that this is a simpler and safer technique to firmly fix the tendon end, compared with the procedure of Pagenstert and colleagues. The single reconstructed calcaneofibular ligament is much closer to the native calcaneofibular ligament.

Furthermore, unlike Coughlin and colleagues [11] who performed single tendon reconstruction of the anterior talofibular ligament with interference screw fixation on the talar insertion, for several reasons, we prefer to create a bone bridge on the talar neck and reconstruct the anterior talofibular ligament in a double fashion. First, it is much closer to the native anterior talofibular ligament. Second, it is much easier to drill a 3.5-mm diameter tunnel than a 6-mm or 7-mm diameter tunnel on the small fibular tip and maintain a strong bone bridge. Our reconstructive technique respects the anatomical feature of ATFL and CFL. This orientation and attachment of the reconstructed ATFL and CFL are similar to those described by Burks and colleagues [9]. With the use of these specific anatomical data, the anatomical sites for ligament attachment can be located more precisely during reconstruction. The main disadvantage of this surgical technique is lack of a biomechanical cadaveric study to verify the benefits of our technique.

With regard to allograft problems, no infections or immunological rejection occurred in our study. Allograft tendons have been widely used for reconstructive surgery, especially in the knee joints, and no infections or immunological rejection have been reported [13–15]. Caprio and colleagues [2] described an augmented reconstructive technique of the ATFL and CFL with a semitendinosus tendon allograft, and they advocated this procedure as a safe, effective method to manage lateral ankle instability.

To decide the surgical treatment, increasingly accurate diagnostic tests are necessary. Lateral ligament rupture of the ankle has ever been diagnosed using stress x-ray image of the talocrural joint. Takao and colleagues [16] performed stress x-ray image of the subtalar joint to decide which ligaments needed reconstruction. In 17 patients, with the talocalcaneal angle less than 10°, only the ATFL was reconstructed; in 4 patients, with the talocalcaneal angle of 10° or more, both ATFL and CFL were reconstructed. After surgery, mean talar tilt angle on stress x-ray image of the talocrural joint decreased significantly in both groups. However, this approach provides only indirect evidence of the lateral stability of the ankle, which may not directly describe the condition of the ligaments. As described before, if osseous architecture is abnormal or dynamic stabilizers are injured, stress radiography results will be positive even though the ligaments are normal. Therefore, it is necessary to use a diagnostic tool to directly assess the ATFL and CFL.

In 2008, Takao and colleagues [17] used magnetic resonance imaging (MRI) to evaluate morphological changes of the ATFL and CFL, demonstrating its usefulness in evaluating the ligaments and directing treatment. The results of MRI are confirmed via arthroscopy, which allows direct visualization of the ATFL and CFL. In contrast, in this study, we used B-ultrasound to assess the ATFL and CFL, which helped us formulate a plan for surgery.

Although MRI has become the preferred tool for evaluating tendons and ligaments [18], B-ultrasound is a uniquely powerful diagnostic tool, with the ability to intensively examine an pathological area during motion [19–22]. The commonly stated shortcoming of so-called operator dependence, on the other hand, becomes a distinct advantage over any of the other radiology tests, particularly in evaluation of the ligaments. The ATFL and CFL have different anatomic characteristics in different people, including origin, insertion, and course direction. Because MRI is limited to three traditional views (axial, sagittal, and coronal), this may unavoidably lead to diagnostic errors because of the scanning slice [23]. In this respect, ultrasound can evaluate the anterior talofibular and calcaneofibular ligaments in any plane and any angle, and trace the ligaments along their entire course. In addition, ultrasound can target the specific site of the patient’s symptom(s) and dynamically observe the underlying structures during motion [24]. Such dynamic evaluation is very useful for the anterior talofibular and calcaneofibular ligaments, because both ligaments have different levels of tension in different people. Therefore, we believe dynamic ultrasound can provide important information for planning surgery. Fibers of the tendons and ligaments can be visualized clearly via ultraound, both before surgery to assess the extent of injury and after surgery to assess the condition of the reconstructed ligaments.

There were several limitations in this present study, including a relatively small sample size, lack of a stress-testing device, no control group, and anatomical reference. When both the ATFL and CFL are injured, we first consider direct repair. If there is not enough soft tissue for repair, we turn to reconstruction. According to the patients’ condition and willingness, the allograft tendon was preferred. Therefore, the number of patients who underwent reconstruction of the ATFL and CFL using allograft appears small. Additionally, we lack a stress-testing device to perform standard stress radiography. Instead, we performed standard stress radiography for the ADT and the inversion test manually. Finally, the anatomical data mentioned in our technique were based on adult patients with average body size. For others, the anatomical data should be adjusted correspondingly.