hta_ knee intro.qxp - Ministero della Salute

1. Background
1.1 Total knee replacement: indication and clinical problem
Osteoarthritis (OA) is one of the most common indications for total knee replacement (TKR). OA
is caused by the damage of the cartilage covering bone surfaces, resulting in a joint which no longer
moves normally. There is usually a progressive increase in pain reported by the patient as the
cartilage degenerates. Initially treatment focuses on drug therapy to reduce inflammation and pain 1 .
Knee replacement may also be considered for rheumatoid arthritis or other inflammatory joint
diseases or following injury. There is a wide variation in the types of prostheses. There is an expected
increase in the utilisation of knee arthroplasty in the future due to a lowering in the average
age of intervention, and an increase in the prevalence of OA as the population ages and life expectancy
increases.
Evidence suggests that women are twice as likely to undergo TKR as men, this could be mainly
attributed to gender-oriented diseases and a higher prevalence of OA amongst women 2 .
The intervention of knee replacement is not without problems and complications can arise
both in the short term such as stiffness, instability or infection and the long term such as prosthesis
wear and aseptic loosening. Complications often result in pain. If one of these complications
occurs, the successive step is the substitution or revision of the failed implant. Revision surgery is
less successful than primary intervention, has a negative impact on the patient’s quality of life, and
represents a burden to the National Health Service.
However it is unclear if obesity and gender are factors directly linked to TKR outcomes as there
is conflicting evidence 2,3 . One of the most important factors affecting outcome is age. The younger
the patient at the time of primary surgery, the higher the subsequent revision rate. This is
almost certainly a reflection of higher activity levels. Some studies suggested that higher numbers
of knee replacements performed by the surgeon and by the hospital annually (throughput), lead
to better outcomes and a lower likelihood of complications 2 .
1.2 Epidemiological data and population
Primary knee replacement is one of the most common surgical orthopaedic procedures undertaken
in Italy today. The data from international registries show that the knee replacement procedures
(total knee replacement and revision) are very common and mainly involve females aged
65 years or more 4-8 . These data refer only to patients in the registries’ survey but are very representative
because the coverage rate is generally high (around 90%). Other studies show the same
trends for age and gender 9-10 .
We analysed the frequency of these procedures in Italy carrying out an analysis of the SDO
database (SDO - hospital discharge records) 11 owned by the Ministry of Labour, Health and Social
Policy (MLHSP).
The aim was to gather data regarding the number of patients discharged for primary total and
revision knee replacement procedures, aged 50 and over (those most likely to have OA of the
knee) from 2001 to 2005.
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