This study aims to describe the spinal sagittal alignment in transfemoral amputees (TFAs) and to compare with a reference population. To our knowledge, this is the first recent radiologic study of the TFAs’ spine and the first postural approach aiming to better understand the height prevalence of low back pain (LBP) in the TFAs.

Volunteers with transfemoral amputation underwent bi-planar X-rays with 3-D reconstructions of the spine and pelvis. Sagittal parameters were analysed in the light of literature and compared to those of a reference group of non-amputees. Differences between TFAs with and without LBP were searched.

Twelve subjects have been prospectively included. The two groups (TFA-LBP: n=5 and TFA- NoP: n=7) were comparable in terms of gender, age, Body Mass Index, amputation delay and sedentarity. In the TFA-LBP group, the impact of LBP was estimated on average at 16.4% with the ODI (SD 7.9%, [6;24]). Pelvic incidences (PI) were within normal limits, except for one TFA-LPB. The pelvic tilt (PT) of all TFAs-NoP was considered to be suitable for PI whereas two TFAs-LBP had inadequate PT. The mean angle of thoracic kyphosis in TFAs-LBP was significantly higher than in TFAs-NoP. All the TFAs-NoP had a lower lumbar lordosis than expected compared to TFA-LBP and the reference population. Concerning the sagittal balance, four of the five TFAs-LBP had unbalanced sagittal posture versus two of the seven in TFAs-NoP. Based on the T9-tilt analysis, the position of the T9 vertebrae is significantly more posterior in TFAs-LBP than in TFAs-NoP.

In the sagittal plane, no TFA-specific abnormalities of the spinal alignment were found. However, it seems that TFAs-LBP more often present a sagittal imbalance. It is not always easy to determine the origin of these sagittal imbalances neither affirming that it comes from the femoral amputation. These origins are certainly multiple (shape of the socket, settings of the prosthesis, preexisting spinal morphology or spinal pathology). This study emphasizes the importance of taking into account the sagittal balance of these patients in order to prevent and manage the onset of low back pain. Moreover, in this population, it would be relevant to focus also on the frontal balance, possibly altered by the lower limbs length discrepancy.