Influence of skin incision position on physiological and biochemical changes in tissue after primary total knee replacement - a prospective randomised controlled trial.

BACKGROUND: Influence of skin incision position on physiological and biochemical changes in tissue after primary total knee replacement. A prospective randomised controlled trial. The blood supply to the skin covering the anterior knee has been shown to arise predominantly from blood vessels on the medial side of the knee. Skin incisions for primary Total Knee Replacement (TKR) positioned medially therefore risk creating a large lateral skin flap that may be poorly perfused. Poorly perfused skin is likely to result in hypoxia at the wound edges and consequently may lead to delayed wound healing and complications. METHODS: We have carried out a randomised controlled trial (n = 20) to compare blood flow on both the medial and lateral sides of two commonly used skin incisions in TKR (midline and paramedian). We have also assessed interstitial biochemistry (glucose, pyruvate and lactate levels) in the presumed at risk lateral skin flap of both incision types. RESULTS: In both incision types tissue hyper-perfusion occurs post-operatively and is maintained for at least 3 days. We found no significant difference between blood flow between the two incision types on the medial side of the incision at either day 1 (p = 0.885) or day 3 post-op (p = 0.269), or, on the lateral side of the incision (p = 0.885 at day 1, p = 0.532 at day 3). Glucose levels are maintained post-operatively in the at risk lateral flap with only minimal changes. Lactate levels rise post-operatively and remain elevated for at least 24 hours. However, the levels did not reach levels suggestive of critical ischaemia in either incision group and no significant difference was observed between incision types. CONCLUSION: We conclude that the use of a paramedian incision results in only minimal biochemical changes, which are unlikely to alter wound healing. TRIAL REGISTRATIONS: ISRCTN06592799 .

Posterior lumbar interbody fusion using cages, combined with instrumented posterolateral fusion: a study of 75 cases.

Posterior lumbar interbody fusion (PLIF) with cages can be combined with decompression of the spinal canal and with instrumented posterolateral fusion (IPLF) with pedicle screws, through a single posterior incision. The authors wanted to assess retrospectively the clinical and radiological outcome of PLIF + IPLF performed by the senior author. Between July 1997 and December 2003, 75 patients underwent PLIF with cages and IPLF with transpedicular instrumentation, for either degenerative disc disease, stenosis, spondylolisthesis or post-discectomy syndrome. The clinical outcome was evaluated according to the criteria of Kirkaldy-Willis. Flexion/extension radiographs and CT-scans were obtained in cases where there was any doubt about the fixation/fusion status. The mean age was 48.7 years (range: 30 to 75). The mean duration of follow-up was 29.17 months (range: 12 to 67). The clinical outcome was excellent or good in 85.3% of the patients. There were 4/75 patients (5.3%) who failed to return to their original occupation. Four posterolateral fusions were uncertain, but all anterior fusions succeeded: thus circumferential fusion was obtained in 71 out of 75 cases, or 94.6%. Three patients sustained a neurological complication, but only one was left with a partial drop foot. The results were comparable with similar studies. Therefore the authors recommend further use of PLIF + IPLF in painful lumbar degenerative spinal disease where conservative management has failed.