20-Bio-A4 Anatomy and Physiology · May 2013
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams May 2013 — 04-Bio-A4 Biomechanics, 3 hours, closed book (approved calculator allowed). Five questions constitute a complete exam paper; each question is of equal value (15 marks).
Reference texts: Winter, Biomechanics and Motor Control of Human Movement (4th ed.); Zatsiorsky, Kinematics of Human Motion; Nordin & Frankel, Basic Biomechanics of the Musculoskeletal System (5th ed.).
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
a) Definitions.
i) Flexion — a sagittal-plane movement that decreases the angle between two body segments at a joint, bringing them closer together (e.g., bending the elbow brings the forearm toward the upper arm).
ii) Abduction — a frontal-plane movement of a limb or segment away from the midline (or reference axis) of the body.
iii) Ulnar deviation — a frontal-plane movement of the hand at the wrist toward the ulnar (little-finger) side; also called wrist adduction.
iv) Internal rotation — rotation of a limb segment about its own long axis such that its anterior surface turns toward the midline of the body (also called medial rotation).
v) Varus angulation — angular deformity in which the distal segment is displaced toward the midline relative to the proximal segment, so the apex of the deformity points away from the midline (e.g., genu varum, “bow-leg”).
b) Condition shown. The photograph shows a firm, bony prominence on the anterior proximal shin, immediately below the knee, in an adolescent girl — the classic presentation of Osgood–Schlatter disease, a traction apophysitis of the tibial tuberosity at the patellar tendon insertion.
c) Muscles addressed. Management centres on the extensor mechanism that transmits the repetitive traction load into the tuberosity: a supervised program of quadriceps and hamstring stretching to reduce tension across the patellar tendon, followed by controlled quadriceps (including vastus medialis obliquus) strengthening as symptoms settle and activity is reintroduced, with temporary activity modification (reduced jumping/running load) during the acute phase.
d) Musculoskeletal risk. The girl is at risk of chronic anterior knee pain and patellar tendinopathy from ongoing traction stress, of a discrete bony ossicle forming within the patellar tendon at the tuberosity (persisting into adulthood), and — in the acute, high-load setting — of a tibial tuberosity avulsion fracture if the apophysis fails outright rather than undergoing chronic remodelling.
