Table 1 Methodological quality assessment

Part A: Only one score to be given for each of the seven sections

1. Study size

4.0

–

2. Mean follow-up

7.86

1.5

3. Surgical approach

9.50

1.2

4. Type of study

4.29

5.3

5. Description of diagnosis

5.00

–

6. Description of surgical technique

10.00

–

7. Description of postoperative rehabilitation

5.00

–

Part B: Scores may be given for each option in each of the three sections if applicable

1. Outcome criteria

1.1 Outcome measures are clearly defined

2.83

1.6

1.2 Timing of outcome assessment is clearly stated

2.33

0.5

1.3 Use of outcome criteria that have been reported to be reliable

2.50

1.0

1.4 General health measure is included

–

–

2. Procedure for assessing outcomes

2.1 Participants are recruited

4.17

0.4

2.2 Investigator is independent of surgeon

1.67

1.5

2.3 Written assessment

3.00

–

2.4 Completion of assessment with minimal assistance

–

–

3. Description of the subject selection process

3.1 Selection criteria are reported and unbiased

3.67

0.91

3.2 Reported recruitment rate  > 80%

3.99

0.9

3.3 Reported recruitment rate < 80%

1.01

0.3