Hi Biomedgator,
Your question is rather ambiguous. Do you mean forces externally applied or internally applied by the muscles? Several research groups (including ours) have measured forces in orthopaedic implants in vivo, during activity. They vary in magnitude according to the particular joint and activity. Other groups have modelled various parts of the musculoskeletal system, to predict the forces generated.
Please be more specific about what you want to know. If it's internal forces I can point you to some papers.
Stevie