Surgical obese patients can expect longer surgery times, longer recoveries and more complications. Surgeons say that getting through the fat layer takes more time, and obesity can often double the length of surgery. The more time a patient spends in the operating room, the greater the chances of complications. 

I am not aware of a formal study correlating length of surgery to weight loss. There is, however, a definite correlation between length of bed-ridden and weight loss. One looses about 7% muscle mass during a good overnight rest. A patient bed ridden for a month can easily loose 40 lbs and be practically unable to rise out of bed under their own power when it is time for them to get moving, this requiring extended rehabilitation with full recovery not ordinarily attainable. I know, because it happened to me.

There must, however, be a (statistical) correlation between weight loss and length of surgery, because long surgeries usually require more bed rest.

Tom

Duration of surgery,including the process of achieving adequate anaesthesia during procedures demand longer periods in the obese.

The ergonomics ie study of people's efficiency in their working environment is further impacted by the patients size or BMI. These are observational points and there are studies that have examined these objectively in different surgical specialties.

Je suis d'accord.

The question was aimed at the article 

https://www.researchgate.net/publication/271535421_Overweight_and_obesity_in_hip_and_knee_arthroplasty_Evaluation_of_6078_cases

where it is said, that there were not more infections in obese patients after arthroplasty and i dont find a solution to the contradiction, that the longer the surgery the more complications is by the above commentaries explained. Thats why I herewith define the question more thoroughly.

Article Overweight and obesity in hip and knee arthroplasty: Evaluat...

i think it varies with the kind of surgery performded as well and how much BMI did they consider in these 6000 pts and what controls they observed  as ordinarily for any abdominal surgery one finds greater morbidity and even in knee and hip surgery since immobilization is boounxd to occur one has to consider what kind of surgeries they took nto account ,which sexes and age groups all factors to be considered before drawing a simple conclusion that there is no effect of BMI on these surgeries. 

Namaste Kulvinder Kaur, 

("Can the people of Jalandhar still see the sun rising?", quote from a person I met in the Punjab)

You are very right and I agree to your thoughts. Am I right, that you propose another study with more comparative surgery? That would be a most difficult task to find the pairs of matching patients to compare with, but maybe such a study with matching pairs would be better with 100 pairs, than with 6000 cases, not to be able to be compared really?

well i will say namaste back as i cant make out whether u r from germany or where although i have practically visited every european country -i dont understand why sun should not come out in jalandhar in fact being very spiritual i believe that since supreme soul is on earth sun will definitely be shining here with him trying to convert kalyug to satyug but coming to ypur point i actually tend to agree with you that atleast matched pairs of say even if not a prospective atleast they can check out retrospectively or by questionaires and even larger data can be sought  as i dont think that obesity and overweight will not have an effect on surgery of knee and hip as both are weightbearing areas and effec has to be there  with physical exercize decreasing so much in obese and osteoporosis sets in and kness usually give in and then for each sex it has tobe appreciated with the effect of hormones and hence age effect etc has to be considered and postmenopausal women will fare worse if obese etc