Knee and hip joint supplier Smith & Nephew posted a rise in second quarter profits but expects its products which serve the younger more active patient segment to face greater challenges. Pre-tax profit increased to $176m in the quarter ended 27 June from $157m in the prior year period. Revenues were slightly lower at $926m compared to $1bn last year.Net debt increased to $1.2bn, primarily due to dividend payments and currency movements. "Our focus on products for younger more active patients has positioned us well over several years. In the current environment this market segment and these products are facing greater challenges," said David chief executive Illingworth."We are confident that our strategy of market led innovation and high customer service levels will position us to achieve above market growth in the future. In the meantime, we are focused on executing our operational improvement plans and delivering profit growth in these tough markets."