Table 3. Comparison of ACL-Injured vs. Control: Males Only.
| Comparison* | Sample (knee) | Mean difference (95% CI) | Significance Z (p-value) | Remark | |
|---|---|---|---|---|---|
| Males (all studies)22-24,33,36,37) | 578 (292 vs. 286) | –0.71 (–1.35 to –0.06) | z = 2.16 (p = 0.03) | Significant heterogeneity needs exploration. | |
| Q = 41.66, df = 5 (p < 0.00001), I2 = 88%, τ2 = 0.55 | |||||
| Males: non-contact (3 studies)23,33,36) | 354 (177 vs. 177) | –1.40 (–1.73 to –1.08) | Z = 8.48 (p < 0.00001) | Subgroup difference Q = 7.48, df = 1 (p = 0.006), I2 = 86.6% | Non-contact ACL-injured males had smaller notch volumes. |
| Q = 2.53, df = 2 (p = 0.28), I2 = 21%, τ2 = 0.02 | |||||
| Males: unrestricted (3 studies)22,24,37) | 224 (115 vs. 109) | –0.08 (–0.97 to 0.81) | Z = 0.18 (p = 0.86) | Subgroup analysis based on mechanism of injury explains heterogeneity. | |
| Q = 13.04, df = 2 (p = 0.001), I2 = 85 %, τ2 = 0.52 | |||||
| Males: injured knee (5 studies)22-24,33,37) | 524 (265 vs. 259) | –0.64 (–1.37 to 0.09) | Z = 1.71 (p = 0.09) | Subgroup difference Q = 0.55, df = 1 (p = 0.46), I2 = 0% | Use of injured or healthy contralateral knee for measurement did not differ significantly. |
| Q = 41.62, df = 4 (p < 0.0001), I2 = 90%, τ2 = 0.62 | |||||
| Males: healthy knee (1 study)36) | 54 (27 vs. 27) | –1.06 (–1.89 to –0.23) | Z = 2.50 (p = 0.01) | ||
| NA | |||||
| Studies using standard method to measure (5 studies)22-24,36,37) | 418 (212 vs. 206) | –0.50 (–1.16 to 0.15) | Z = 1.51 (p = 0.13) | Subgroup difference Q = 8.46, df = 1 (p = 0.004), I2 = 88.2% | Method of measurement does not explain heterogeneity adequately. |
| Q = 23.73, df = 4 (p < 0.0001), I2 = 83%, τ2 = 0.45 | |||||
| Other methods33) | 160 (80 vs. 80) | –1.62 (–1.99 to –1.25) | Z = 8.64 (p < 0.00001) | ||
| NA | |||||
| Matched controls (4 studies)22,23,33,36) | 444 (222 vs. 222) | –1.21 (–1.61 to –0.81) | Z= 5.95 (p < 0.00001) | Subgroup difference Q = 6.93, df = 1 (p = 0.008), I2 = 85.6% | Because notch volume is unlikely to vary with age in adults, this association may be spurious. |
| Q = 7.52, df = 3 (p = 0.06), I2 = 60%, τ2 = 0.10 | |||||
| Unmatched controls (2 studies)24,37) | 134 (70 vs. 64) | 0.32 (–0.75 to 1.38) | Z = 0.59 (p = 0.56) | ||
| Q = 4.70, df = 1 (p = 0.03), I2 = 79%, τ2 = 0.47 | |||||
ACL: anterior cruciate ligament, CI: confidence interval, Q: Cochrane's Q statistic (χ2), df: degrees of freedom, τ2: tau2, NA: not available.
*All analyses used inverse-variance weighted random effects model. Unit of Effect measure: mean difference in cm3.
Statistically significant, p < 0.05.