Abstract
Sir: First we would thank Dr Salawu and Dr Neumann for their comments, and for taking an interest in our study.
The main purpose of our study on three trans-humeral traumatic amputees was to surgically modify the amputation stump, with which we could supply the patient with a new type of prosthetic socket without harness and straps.
To surgically modify the amputation stump we used a cemented implant. The survival of cemented implants, as artificial hip joints, is well documented (Havelin et al. 2000; Malchau et al. 2002). A cemented hip arthroplasty can withstand decades of compression, traction and rotational forces. In our study we used a similar high-pressure cementing technique as in prosthetic joint surgery. The fact that we employed such a well-documented technique for fixating the implant was probably the main reason that our study was approved by the Regional Ethical Committee. We performed mechanical testing in vitro to study the response to maximum axial and torsional load. At least theoretically, this is more relevant to a trans-humeral amputee compared to a patient with a cemented hip implant.
When the patients were included in the study their prosthetic function was suboptimal. Preoperatively, we performed different testing according to modified Disabilities of the Arm, Shoulder, and Hand (DASH) Outcome Measure, and ADL testing with the prosthesis. However, the most significant result was the increased ROM of the ipsilateral glenohumeral joint, and a decrease in the level of pain and discomfort from the neck and the contralateral shoulder. This was due to use of a new type of prosthetic socket with adjustable pressure control around the artificial condyles, and no harness and straps.
Based on the results of the present case series we have continued the clinical study, and our plan is to include 10 patients. Due to the poor result in patient number three we do not include patients with short amputation stumps, and we do not use implants with an intercondylar diameter larger than 60 mm. With this, we hope to be able to publish a more thorough study of this new technique for prosthetic fitting in trans-humeral amputees.
Eivind Witsø
Department of Orthopaedic Surgery
St Olav's University Hospital
Trondheim, Norway