A standardised hand function test based on seven of the eight most common hand grips is reported. The test consists of 20 activities of daily living. The test procedure and the method of scoring are described as is our evaluation of the validity and reliability of the test. Fifty-nine tetraplegic patients were evaluated using the test before reconstructive surgery to their hands. The test score correlated well with the accepted international functional classification of the patient's arm (r = 0.76, p < 0.001). The mean test score in the arms of patients lacking sensation was significantly lower than in those with tactile gnosis (O:1-3 compared with OCu:1-3, p < 0.001).

Forty-three children with 46 lacerations of the flexor digitorum profundus tendon were evaluated at a mean of five and a half years (range three to 10) after tendon repair. Postoperatively, 27 digits were treated with early controlled mobilisation as described by Kleinert and 19 digits were immobilised in plaster. Thirty-one digits were primarily repaired within 24 hours, and in 15 digits repair was delayed. The return of total active motion (TAM) in the interphalangeal joints was evaluated with the Strickland formula, and the mean was 77%. TAM correlated with the age of the child at the time of injury. Variables such as postoperative regimen, concurrent injury to the superficial tendon or digital nerve, delayed tendon repair, localisation of injury in the fibro-osseous canal, and type of trauma, had no significant effect on the final result.

Twenty-one patients with revascularized/replanted amputated parts of the upper limb were studied for an evaluation of hand function. Two patients had been injured at the lower arm to wrist level, four between the wrist and MCP joint, three distal to the MCP joints in thumbs and/or fingers, and twelve in the thumb only. Hand function was measured as grip and pinch strength, range of movement (ROM), sensibility (two point discrimination), and Sollerman test score. Cold sensitivity as related to circulatory changes in the replanted limb was evaluated in six patients using the critical opening test (COP). Twelve of 17 initiated replantations (71%), and 11 of 12 revascularizations (92%), were successful. Hand function was restricted in patients with amputations at the lower arm to wrist level, fair in replanted midhands, good, but with wide variations after replantations at the MCP or distal II-V fingers, and best of all in replanted thumbs. Sensibility was poor in a majority of the patients. Three out of six of the patients who were COP-tested had significantly reduced blood pressure in the replanted part. The test results (grip, ROM, Sollerman score) in three patients with amputated thumbs were not found to differ greatly from those with replanted thumbs. These results raise the question of whether the Sollerman test underestimates the importance of the thumb or whether the thumb is overestimated in hand function.

At its most basic, biomechanics is the study of the effects of bending, twisting, pulling, pushing and rubbing (shear) forces on living tissue. These effects provide, as limits, a mechanical description of biological tissue; as they relate to loading experienced in vivo, they describe the mechanical milieu in which living tissues operate. To the extent that the latter affect the former, one can speak of a "Wolff's Law of Soft Tissue", to describe the effect of function on form. Within the realm of hand surgery, no topic exceeds tendon injury and repair in the wealth of biomechanical data available, the thought that has gone into the analysis of that data, and the knowledge that has been gained as a result. This review will summarize the influence of biomechanical thought and research on the management of flexor tendon injury. Conceptually, the loads applied to tendons physiologically become the lower limit for the material properties of the tissue, if it is to function normally. Thus it is relevant to know the tensile strength of normal tendon, of various tendon repairs, and the loads that might be applied to healing tendons either during daily activity or with rehabilitation. Tendon repairs commonly fail by breaking at some point during the healing period. In vitro studies have shown that thicker core sutures, repairs with more strands crossing the laceration, and repairs with locking loops are stronger, and such repairs have been adopted clinically. A running peripheral suture does not increase the ultimate breaking strength much, but does increase the load needed to cause the repair to gap, especially when the running suture is locked. This may be useful as well, for several mechanical reasons discussed below, and on the basis of these mechanical studies, peripheral finishing sutures have been incorporated into tendon repairs, although the details of such sutures remain subject to discussion. Tendon repairs have also been studied in vivo, in animal models. It has been known since the 1940s, when Mason and Allen wrote their classic study, that repairs tend to weaken for the first few weeks, especially in immobilized tendons. More recently, it has become clear that this effect can be moderated considerably if tendons are moved postoperatively, and so early motion regimens have become incorporated into all tendon rehabilitation protocols. Whether loading of the tendon is also important remains controversial. Loading clearly stimulates isolated tendon cells and, in some cases, tendon tissue in vitro, but the results of loading programs in vivo, either in animal models or in clinical studies, have been unimpressive when compared to similar protocols which assure motion, but with minimal loading. Some unanticipated findings have been noted in the studies of partial tendon injuries, which again have influenced clinical practice. For partial lacerations that affect less than 90% of the tendon cross-section, a repair results in a weaker tendon postoperatively than no repair. Even

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