NHS Trusts can save £664m from the total they spend on joint surgery over the next 10 years, according to an exclusive analysis made available on hsj.co.uk.

Data collected by analysts Sg2 looked at how much could be saved in different regions by changing care pathways for joint replacement surgery. This involves reducing the length of stay of all providers to the average of 5.8 days found at NHS treatment centres which focus on elective procedures. The trust average is 7.3 bed days.

Many primary care trusts are reducing access to elective hip and knee operations to make savings. However the data suggests more than 1.7 million bed days could be saved over 10 years without cutting referrals or requiring extra investment.

The North West region has the most to gain through improved pathways for joint replacements, with cumulative 10 year savings of over £90m, according to the data. The South West could save £86m.

Broken down to PCT level, NHS Hampshire could save £18m and NHS Devon could save £15m over 10 years.

The data also shows that the best practice tariff reduction for 2011-12 could cost acute providers £23m next year in lost income for primary hip and knee replacements alone.

The biggest losses from the tariff change for joint replacements are at Gloucestershire Hospitals Foundation Trust, which will lose £409,000, and Wrightington, Wigan and Leigh Foundation Trust where £400,000 will be lost.

Sg2 identified seven trusts that can expect a fall in income from joint replacements of more than £300,000 in 2011-12 and have average lengths of stay furthest above the 5.8 days threshold.