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Articular geometry of the tibia has been studied in relation to the functional axis and extra-articular bone landmarks, using a Cartesian coordinate system. Thirty-one cadaver limbs were used, 26 of them paired. The donor age range was 61 to 89 years (17 females, 14 males), none of whom showed evidence of significant arthritic deterioration. Most linear parameters were greater in males than females (p less than 0.005), and correlations between these parameters were noted, e.g., tibial length versus plateau width (r = 0.7, p less than 0.01) with both genders combined. Gender differences occurred in only two of the angular parameters--tibial torsion (p less than 0.025) and foot rotation (p less than 0.005). For the latter, mean rotation was internal (-5 degrees) for males, and external (11 degrees) for females. No correlations between angular parameters were found. In the paired limbs, there was asymmetrical distribution of just two parameters--varus tilt of the tibial plateau margins (p less than 0.005) and lateral deviation of the tuberosity (p less than 0.025). The data complement a previous report on the femur. These studies are relevant to the kinematics of the lower limb, design and sizing of resurfacing components, and possibly to the pathogenesis of osteoarthritis.

A method is described which provides standardised reproducible radiographic images of the lower limb. Anteroposterior and lateral radiographs are digitised and processed by computer to provide graphic/numeric displays of angles and linear measurements, relating the centre points of the hip, knee, and ankle. Two cases illustrate how surgical planning is facilitated when standardised data are available. These data confirm the close relationship between postoperative limb alignment and positioning of prosthetic elements.

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Clinical results with elbow prostheses have been disappointing. A detailed knowledge of elbow joint geometry and mechanics is necessary to improve prosthetic design. In this study, the humeroulnar articulation of four human cadaver elbows was examined using surface analytic methods. In this article, the location of the transverse axis of elbow flexion-extension is suggested in relation to well-defined landmarks, the medial and lateral epicondyles, and subsequently to the line connecting their most lateral points--the transepicondylar line. The geometry of the structures responsible for the carrying angle is discussed, as is the extent of cartilage-covered bearing areas of the lower humerus and upper ulna. Implications pertaining to prosthetic design and surgical technique resulting from this study are discussed.