Easy technique for radiographic evaluation of stump-socket fit in below-knee amputees

Background. The alignment of a prosthesis affects the way load is transferred to the stump through the socket; this is critically important for its comfort and function. The aim of the study was to assess the value of radiopaque materials in evaluation of stump-socket fit in people with below-knee amputation. Material and methods. Thirty-two amputees (skin breakdown group) had cutaneous lesions in the stump, and another 26 amputees (control group) had no lesion in the stump after training with their prosthesis. Metallic markers were attached to weight-bearing points in the internal socket. X-rays were taken in the antero-posterior and lateral projections. Results. In the antero-posterior view, the weight-bearing points of the stump did not correspond to the metallic markers placed over the patellar tendon and the tibial tuberosity points in the socket in 78.1% of the 32 amputees in the skin breakdown group. This malalignment was present in 42.3% of the 26 amputees in the control group (Pearson Chi-Square, p<0.007). In the lateral view, in 65.6% of the 32, the weight-bearing points of the stump did not correspond to the metallic markers placed over the patellar tendon and the tibial tuberosity points in the socket. This malalignment was noted in 23.1% of the 26 patients in the other group (Pearson Chi- Square, p<0.002). Conclusions. 1. The conflict between the prosthesis and residual limb is the cause of skin disruption at different sites of the stump and can be successfully treated by prosthetic socket modification. 2. Efforts should be made to systematically identify any discrepancies between the stump and the soc ket. 3. Correct adaptation of the prosthesis to the weight-bearing points of the stump will offer clinicians the possibility of quantification and visualization of this interaction using simple radiographic techniques.