Outcomes of knee disarticulation and the influence of surgical techniques in dysvascular patients : report of a systematic review

Background: Dysvascularity is the main cause of lower limb amputations in Scotland and there is an insignificant proportion (1.7%) of knee disarticulation (KD), despite the benefits of the amputation. Objectives: The outcomes of KD and its associated techniques will be evaluated based on quality of stump, functional outcomes, prosthetic ambulation and gait biomechanics, to determine if a greater rate of KD can be justified among dysvascular patients. Methods: Medline, Embase, Cochrane Library and Science Direct were searched for the relevant literature based on a pre-specified eligibility criteria. Studies were critically appraised and data extraction/synthesis were carried out. Results/ Quality appraisal: SIGN 50 Grade of Recommendation, C. 17 studies reported on the quality of stump. Healing rates are comparible to trans-femoral levels of other studies. However, there are risks of reamputations if the method of amputation level selection is inappropriate. The key is to have ancillary physiologoical tests to supplement clinical judgements during selection. Functional Outcomes: Four studies reported on functional outcomes, which were pooere with more proximal amputations. Trans-femoral patients had poorer maintenance of preoperative independent status than KD patients, however results were only from a 1-year follow-up periosd. Prosthetic Ambulation: Nine studies reported on prosthetic ambulation. Ambulation rates vary largely across studies, however most patients had limited preoperative mobility and it would be more accurate to indicate the maintenance of ambulatory multi-disciplinary involvement in the research teams. Gait Biomechanics: two studies reported on gait biomechanics and walking capacity decreased with more proximal amputation levels. One study indicated that KD provided greater stabilioty than trans-tibial levels for dysvascular patients, but the evidence was insubstantial. Overview of Surgical Techniques: The anterior flap is unsuitable for dysvascular patients. Theoretically, the posterior flap allow3s better vascularisation and padding than sagittal flaps, but there was no direct comparisons between both techniques. The Mazet technique is potentially propitious in the quality of stump and prosthetic ambulation, but more robust study designs are required to justify that the technique is suitable for dysvascular patients. Gritti-Stokes amputations had low re-amputation rates, but controversial ambulation rates, and may be suitable for non-ambulatory patients. Recommendations: The overall strength of evidence of current literature is low and further creditable research is required to determine if a greater proportion of KD’s can be justified among dysvascular patients with comparisons to different amputation levels and the inclusion of results from long-term follow-up periods. Variable have to be fully identified and accounted for in multivariate analyses as rehabilitation outcomes are multifactorial. If prosthetic ambulation is measured, the involvement of prosthetists and physiotherapists with the use of validated mobility scales are necessary