Table 2.

Summary of included studies

Study (author and year)	Subject features	Age	Gender	Time from injury to study commencement/duration when patients presented with symptoms	Study design	Level of evidence	Index tests	Gold standard	Main conclusion
Cha et el. 2012	65 patients diagnosed with chronic lateral ankle instability who received preoperative MRI and arthroscopic examination	Not mentioned	39 men and 26 women	Not mentioned	Case-control study	3b	MRI	Arthroscopic findings	“However, inter-observer reliability and sensitivity of MRI findings were found to be relatively low in this study. Therefore, arthroscopic examination before ligament repair is a useful and recommended method for diagnosis and treatment of intra-articular lesions.”
Chandnani et al. 1994	17 chronic ankle instability patients	24.5 years (ranged from 20 to 48 years)	14 men and 3 women	Presented with symptoms of at least 6-months duration and did not respond to conservative therapy that included immobilization and early aggressive rehabilitation	Cohort study	2b	Stress radiograph, MRI and MR arthrography	Findings from either diagnostic arthroscopy (n = 3) or open surgical repair (n = 14)	“In conclusion, our results suggest that MR arthrography may be a sensitive technique for detecting and staging tears of the lateral collateral ligaments and evaluating associated injuries in patients with chronic ankle instability. In patients for whom surgery is contemplated, MR arthrography may be a useful adjunct to conventional imaging techniques.”
Cheng et al. 2014	120 patients with a clinical suspicion of chronic ankle ligament injury	32 years (ranged from 15 to 70 years)	85 men and 35 women	Duration of symptoms ranged from 6 weeks to 20 years (mean, 2.2 years)	Cohort study	2b	Ultrasonography	Arthroscopic findings (42 of these patients also underwent open surgery)	“In conclusion, ultrasonography as a convenient technique with low costs and real-time examination showed a satisfactory sensitivity and specificity for detecting lateral ligament injury.”
Cho et al. 2016	28 consecutive lateral ankle instability patients who underwent ankle arthroscopy	32.4 ± 11.9 years (ranged from 15 to 55 years)	19 men and 9 women	Conservative treatment had failed to substantially alleviate the symptoms for at least 3 months	Case-control study	3b	MRI, manual anterior drawer test, stress ultrasonography, and stress X-ray	Arthroscopic findings	“Manual stress US is as precise as MRI in the detection of ligament injury and provides information on chronic ankle instability.”
Chou et al. 2006	50 patients suffering from ankle instability (17 of them who would receive surgical intervention were included in this review.)	Ranged from 14 to 77 years, n = 50	29 men and 21 women, n = 50	Not mentioned	Cohort study	2b	MRI and MR arthrography	Surgical findings	“For evaluating ankle disability, using plain MRI alone is not adequate for correctly detecting lateral collateral ligamentous injury of the ankle joint. MR arthrography improves the sensitivity and the accuracy for ATaF and CF ligament injuries. It also helps in assessing coexisting pathologic lesions of ankle joints.”
Hua et al. 2012	83 consecutive patients underwent ankle arthroscopy for different diagnosis	32.2 years (ranged from 17 to 57 years)	51 men and 32 women	Not mentioned	Case-control study	3b	Ultrasonography	Arthroscopic findings	“US examination is a reliable and accurate method to evaluate chronic ATFL injury.”
Joshy et al. 2010	24 patients underwent arthroscopy as well as MRI for chronic ankle pain and/or instability	39 years (range from 11 to 65 years)	12 men and 12 women	Not mentioned	Case-control study	3b	MRI	Arthroscopic findings	“MRI scan has very high specificity and positive predictive value in diagnosing tears of ATFT, CFL and osteochondral lesions. However sensitivity and negative predictive value is low with MRI.”
Kim et al. 2015	79 patients who would undergo ankle arthroscopy for different diagnosis.	34.6 years (ranged from 21 to 67 years)	44 men and 35 women	Mean duration of symptoms was 25.9 weeks (range, 11 to 52 weeks)	Cohort study	2b	MRI	Arthroscopic findings	“The specificity and positive predictive value of MRI in the diagnosis of ATFL injuries were very high, whereas the sensitivity and negative predictive value of MRI were relatively low.”
Kumar et al. 2007	58 patients with symptomatic instability of their ankle	28 years (ranged from 18 to 50 years)	47 men and 11 women	Unresponsive to physiotherapy and non-operative management for at least 6 months	Cohort study	2b	MRI and stress radiography	Arthroscopic findings	“MRI did not demonstrate any distinct advantage over the examination under anesthesia and stress radiography in the diagnosis of grade III lateral ankle ligament injuries.”
Lee et al. 2012	34 patients who underwent ankle MRI because of ankle sprains or ankle instability	29 years (ranged from 13 to 53 years)	22 men and 12 women	Not mentioned	Cohort study	2b	MRI	Arthroscopic findings	“|A cortical defect with a bright dot-like or curvilinear high-signal-intensity lesion on T2-weighted MRI may be regarded as an additional finding to help increase the diagnostic performance for detecting anterior talofibular ligament injuries, including partial tears.”
Oae et al. 2010	34 consecutive patients needed an operation because of severe problems such as osteochondral lesions, synovitis and instability (15 chronic cases of them were included in this review.)	29 years (ranged from 13 to 55 years), n = 34	19 men and 15 women, n = 34	With a history of ankle injury of more than 4 weeks	Cohort study	2b	Stress radiography, ultrasonography, and MRI	Arthroscopic findings	“We obtained satisfactory results with US and MR imaging.”
Park et al. 2012	48 people suspected of chronic ankle ligament injury	36 years (ranged from 19 to 64 years)	25 men and 23 women	The duration of symptoms ranging from several months to several years	Cohort study	2b	MRI	Surgical findings	“In conclusion, MRI does not show perfect sensitivity for the evaluation of chronic lateral ankle ligament injury, such as those to the ATFL and CFL. Diagnosis of a complete tear of the ATFL on MRI is more sensitive than the diagnosis of a complete tear of the CFL. MRI findings of CFL injury were diagnostically specific but were not sensitive.”
Staats et al. 2017	30 patients with CAI and failed conservative treatment	39.1 years (ranged from 18 to 71 years)	15 men and 15 women	Not mentioned	Cohort study	2b	MRI	Arthroscopic findings	“MRI is a helpful tool for preoperative evaluation, but arthroscopy remains gold standard in the diagnosis of associated lesions in patients with CAI”
Sugimoto et al. 2002	37 ft of 35 patients in whom recurrent instability of the ankle was diagnosed	29.1 years (ranged from 11 to 56 years)	16 men and 19 women	Mean interval between the injury and arthrography was 4 years 3 months (range, 6 months–22 years)	Cohort study	2b	Subtalar arthrography, manual anterior drawer test and talar tilt test	Surgical findings	“Subtalar arthrography is valuable in making the diagnosis of calcaneofibular ligament injury in recurrent instability of the ankle.”
Tan et al. 2017	82 patients with ankle inversion trauma history (42 in the chronic group were included in this review.)	24.8 years (ranged from 17 to 48 years), n = 42	36 men and 6 women, n = 42	Interval from time of injury to time of MRI more than 3 months	Cohort study	2b	MRI	Surgical findings	“MRI was able to accurately diagnose lateral ankle ligament tears in most cases. Diagnosis of a complete ATFL tear on MRI is more sensitive than that of complete CFL tear. The MRI findings of CFL injury were diagnostically specific but were not sensitive.”