Given the growing prevalence of obesity around the world and its association with osteoarthritis of the knee, orthopaedic surgeons need to be familiar with the management of the obese patient with degenerative knee pain. The precise mechanism by which obesity leads to osteoarthritis remains unknown, but is likely to be due to a combination of mechanical, humoral and genetic factors. . Weight loss has clear medical benefits for the obese patient and seems to be a logical way of relieving joint pain associated with degenerative arthritis. There are a variety of ways in which this may be done including diet and exercise, and treatment with drugs and bariatric surgery. Whether substantial weight loss can delay or even reverse the symptoms associated with osteoarthritis remains to be seen. . Surgery for osteoarthritis in the obese patient can be technically more challenging and carries a risk of additional complications. Substantial weight loss before undertaking total knee replacement is advisable. More prospective studies that evaluate the effect of significant weight loss on the evolution of symptomatic osteoarthritis of the knee are needed so that orthopaedic surgeons can treat this patient group appropriately.

Intravenous tranexamic acid (TXA) has been shown to be effective in reducing blood loss and the need for transfusion after joint replacement. Recently, there has been interest in applying it topically before the closure of surgical wounds. This has the advantages of ease of application, maximum concentration at the site of bleeding, minimising its systemic absorption and, consequently, concerns about possible side-effects. We conducted a systematic review and meta-analysis which included 14 randomised controlled trials (11 in knee replacement, two in hip replacement and one in both) which investigated the effect of topical TXA on blood loss and rates of transfusion. Topical TXA significantly reduced the rate of blood transfusion (total knee replacement: risk ratio (RR) 4.51; 95% confidence interval (CI): 3.02 to 6.72; p < 0.001 (nine trials, I. 2 . = 0%); total hip replacement: RR 2.56; 95% CI: 1.32 to 4.97, p = 0.004 (one trial)). The rate of thromboembolic events with topical TXA were similar to those found with a placebo. Indirect comparison of placebo-controlled trials of topical and intravenous TXA indicates that topical administration is superior to the intravenous route. In conclusion, topical TXA is an effective and safe method of reducing the need for blood transfusion after total knee and hip replacement. Further research is required to find its optimum dose for topical use. Cite this article: Bone Joint J 2014;96-B:1005–15

Modern healthcare contracting is shifting the responsibility for improving quality, enhancing community health and controlling the total cost of care for patient populations from payers to providers. Population-based contracting involves capitated risk taken across an entire population, such that any included services within the contract are paid for by the risk-bearing entity throughout the term of the agreement. Under such contracts, a risk-bearing entity, which may be a provider group, a hospital or another payer, administers the contract and assumes risk for contractually defined services. These contracts can be structured in various ways, from professional fee capitation to full global per member per month diagnosis-based risk. The entity contracting with the payer must have downstream network contracts to provide the care and facilities that it has agreed to provide. Population health is a very powerful model to reduce waste and costs. It requires a deep understanding of the nuances of such contracting and the appropriate infrastructure to manage both networks and risk.

Cite this article: Bone Joint J 2017;99-B:1431–4.