Constantly kneeling, squatting, and getting up and down stresses the knees and is a work hazard for floor layers. While the possibility of knee injury and degeneration in this trade is obvious, the first comparative magnetic resonance imaging (MRI)/clinical study has just been completed in Arrhus, Denmark by S. Rytter et al (J Rheumatol. 2009; 36:1512-1519).
Two trade groups were studied, both unionized and with contrasting work positions. A self-administered questionnaire was sent to and received from 253 floor layers and 290 graphic designers to create orthopometric, employment, knee complaints, and sport activities data. Random samples of those respondents (92 floor layers and 49 graphic designers) underwent MRI of both knees, and statistical analyses were performed. The ages ranged from 42 to 70 years with a mean age of 55.6 years.
Laying floors includes installing linoleum, vinyl, and carpet after removing old floors, priming, grinding, gluing, etc. Graphic designers work largely standing at visual display units.
During knee flexion, there is a significant load imbalance between the forces on the lateral and on the medial tibial-femoral contact areas. It is created by an adduction moment. These forces increase with deep knee flexion. Medial compartment pressures are up to 70% more than lateral. In addition, the lateral meniscus is more free to move. The posterior horn of the medial meniscus is restricted by soft tissue attachments.
The authors found meniscal degeneration tears, more medial than lateral meniscal tears, and more bilateral damage to be significantly more common in floor layers than in graphic designers, confirming with MRI support, the occupational hazard of floor laying.
|Blue Notes Editor:|
Charles Sorbie, MB, ChB, FRCS(E), FRCS(C)
Dr. Charles Sorbie is Professor of Surgery at Queens University and a member of the Attending Staff at the General and Hotel Dieu Hospitals in Kingston, Ontario.
A former chairman of the Department of Surgery at Queens University, Dr. Sorbie has been President of the Canadian Orthopaedic Research Society, the Canadian Orthopaedic Association, and the Societé Internationale de Chirurgie Orthopédique et de Traumatologie (SICOT).