Blood flow rate of the peripheral nerve was measured using the hydrogen washout technique and the effects of dissection, stretching and compression were studied on blood flow of the rabbit sciatic nerve. Regional surgical dissections revealed that a proximal portion of the sciatic nerve receives its blood supply from gluteal vessels whereas a distal portion receives from popliteal vessels. Blood flow direction in the proximal half of the sciatic nerve in the thigh was found to be distal whereas in the distal half to be proximal. The longitudinal pathway appeared to be capable of compensating for local diminution of blood flow. The average stretching of more than 15.7% caused complete arrest of blood flow in the stretched nerve. The average stretching force at this point was 74 grams. Complete standstill of intraneural circulation was observed under compression of 50 to 70 mm Hg, or 60 to 80% of mean arterial pressure. These values of critical stretching and compression on the intraneural blood flow corresponds well with those previously reported by Lundborg, 1973; Rydevik, 1981).
The use of standing radiographs to determine correction angles for high tibial osteotomy is not appropriate because the relative angle of the articular surfaces (condylar-plateau angle) in the weight-bearing knee changes after the osteotomy. This may give unpredictable results postoperatively. We found that the condylar-plateau angle in postoperative standing films is very similar to that seen in non-weight-bearing supine views, and suggest that these latter radiographs be used for pre-operative planning. We describe our early results, using a special osteotomy jig, in 140 knees.
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