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Poster: 29In Vivo Measurement of Pennation Angle of the Vastus Lateralis andMedialis Muscles in Knee Arthroplasty*Tomohiro Goto - Tokushima Red Cross Hospital - Komatsushima, Japan*Email: tomogoto@mbr.nifty.comImpairment of muscle strength just after knee arthroplasty is predominantly due to failure ofactive muscle contraction. However, how the failure of muscle contraction during this periodhas not been well documented. Vatus lateralis (VL) and medialis (VM) are pennate muscle. Inthe pennate muscle, pennation angle between the deep aponeurosis and fascicle increases withmuscle activation. Therefore, muscle activation can be roughly estimated by measuring thechange of pennation angle of VL and VM using ultrasonography.Nine knees in nine patients (mean age, 72.0 years; range, 61-82 years) who received kneearthroplasty were included in this study. All the patients were female. Seven patients wereosteoarthritis and two patients were rheumatoid arthritis. Six patients who underwent TKA withthe medial parapatellar approach and three patients who received UKA with the subvastusapproach were measured before and at a week after surgery. Ultrasonic measurement wasperformed both at rest and maximal muscle contraction.From all the subjects, we could clearly observe the fascicles and aponeuroses for measuringpennation angles in ultrasonic images obtained from both VL and VM [Fig. 1]. Preoperativechanges of pennation angles from at rest to contraction were 5.23°, 4.16°, 4.96° and 5.95°onaverage for the VL operated, VL non-operated, VM operated and VM non-operated limb,respectively. These angles decreased by 25%, 11%, 33% and 14% at a week after surgery.All the patients showed that the ability of quadriceps muscle contraction has decreased in theoperated limb. Although we could not draw a specific conclusion in the present study becausesample size was too small, this study demonstrated that quadriceps contraction ability just afterknee arthroplasty could be measurable by using ultrasonography. Ultrasonography is superior toother methods in terms of availability and non-invasiveness. We believe that assumption of datausing ultrasonography regarding how the failure of voluntary muscle activation just after thesurgery will greatly contribute to develop the surgical techniques and rehabilitation methods.Poster: 30Preliminary Clinical Results of Patient Specific Cutting Guides for TotalKnee Replacement (TKR)*Mahmoud Hafez - October 6th - Cairo, Egyptfile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]