Estimating effect size using Cohen's d, we found that the knee-disarticulation amputation group reported less current phantom limb pain on the 0-10 numeric rating scale than the transfemoral amputation group (d = -0.
Estimating effect size using Cohen's d, we found that the knee-disarticulation amputation group had less current residual limb pain on the 0-10 numeric scale than the transtibial amputation group (d = -0.
Of the 42 patients enrolled in the study, 24 patients reported troublesome back pain since their amputation: 8 in the transfemoral amputation group, 6 in the transtibial amputation group, and 10 in the knee-disarticulation amputation group.
In terms of amount of interference with daily activities over the past 3 months because of back pain, the knee-disarticulation amputation group reported less interference than the transfemoral amputation group (d = -0.
The findings from the current study demonstrate that individuals who underwent knee-disarticulation amputation have pain and pain-related interference outcomes similar to those of rigorously matched populations of individuals with either transtibial or transfemoral amputations.
Most recently, knee-disarticulation amputations have fallen out of favor in the trauma population in part because of the results from the LEAP study  that demonstrated worse outcomes with knee-disarticulation amputations than with transtibial and transfemoral amputations in a trauma population.
Another potential explanation for the difference in findings is that in the LEAP study, 17 of the 18 patients in the knee-disarticulation amputation group had their amputation at the zone of injury level, which may have affected short-term healing and function.
Although our study and the LEAP study had a comparable number of participants with knee-disarticulation amputations (16 in the final analysis of the LEAP trial vs 14 in this study), the LEAP trial compared these patients with a much larger sample of subjects with transtibial amputation (81) and transfemoral amputation (27) rather than using a matched case design, as was done in our study.
In conclusion, our study of a sample of primarily male, Caucasian, and middle-age-to-elderly adults with amputations found no significant differences between knee-disarticulation amputations and either transfemoral or transtibial amputations in terms of phantom limb pain, residual limb pain, back pain, or pain-related interference outcomes.
While the current study found that persons with knee-disarticulation amputation do not have significantly worse pain or pain-related interference outcomes than do persons with transtibial or transfemoral amputation, some limitations affect this study.