By: 1 October 2007

The National Joint Registry 4th Annual Report is the formal public report of the National Joint Registry for 1st April 2006 to 31st March 2007. In addition it contains an analysis of the data held on the Registry.

The National Joint Registry (NJR) was established to improve care for patients who require hip and knee joint replacement implants and surgery. It does this by collecting data that can be used to measure the long-term effectiveness of implants used in hip and knee joint replacement surgery and information about the surgical procedures involved. Below are the the facts and figures from the report.

NJR Procedure figures for 2006

The compliance rate was 79% for procedures in the NHS and the independent sector, compared with 77% in 2005 and 60% in 2004.

415 NHS and independent sector hospitals and treatment centres were open and 393 (95%) submitted data to the NJR. On average, 112 hip replacements and 99 knee replacements were recorded per participating healthcare unit.

The NJR recorded 61,456 hip replacement procedures, of which 10% were revisions or re-operations, and 60,986 knee replacement procedures, of which 8% were revisions or re-operations.

Of the hip procedures, 65% were carried out in NHS hospitals, 25% in independent hospitals, 5% in NHS treatment centres and 4% in independent sector treatment centres.

Corresponding percentages for knee procedures were 67% in NHS hospitals, 21% in independent hospitals, 7% in NHS treatment centres and 5% in independent sector treatment centres.

Procedure Statistics

Patients with mild disease or more severe comorbidity increased from 68% in 2004 to 76% in 2006 in patients undergoing primary hip replacement, and from 74% to 82% undergoing primary knee replacement.

Cementless hip replacements increased from 21% in 2004 to 30% in 2006 and cemented replacements declined from 53% in 2004 to 48% in 2006.

155 different brands of acetabular cups and 176 brands of femoral stems were recorded, compared with 110 cups and 129 stems in 2005 and 88 cups and 101 stems in 2004. 22% of all cup and stem procedures used 'mixed and matched' cup-stem combinations.

54 brands of total condylar knee prostheses were recorded, with 13 unicondylar prostheses, 7 patello-femoral replacement and 12 hinged prostheses – an increase of about 50% compared with 2004.

Procedures between 1st April 2003 and 30th September 2006

The overall revision rate for primary hip replacement was 0.7% at 1 year and 1.3% at 3 years.

Procedure type was the most influential factor on implant survival following primary hip replacement. 1 year revision rates after hip resurfacing (1.6%) were five times higher than cemented total hip replacement (0.3%).

Hip resurfacing procedures still have a statistically higher revision rate within 1 year compared with cemented THR. A large number of the failures of hip resurfacing prostheses were in older female patients.

The overall revision rate for primary knee replacement was 0.4% at 1 year and 1.4% at 3 years. Revision rates at 1 year were similar between cemented total knee (0.3%) and unicondylar knee primary replacements (0.4%).

Mortality at 1 year was 1.9% after hip replacement and 1.6% after knee replacement, less than half of that observed in the matched general population, showing that joint replacement patients are a highly select group.

A thromboprophylaxis regime was prescribed for 74,868 (98%) of primary hip replacement patients and 76,581 (98%) of primary knee replacement patients. There was no difference in mortality up to 1 year between patients who were prescribed thromboprophylaxis and those who weren't.

Average length of hospital stay

Primary hip replacement 9.1 days
Hip resurfacing 6.3 days
Primary knee replacement 8.1 days
Unicondylar knee replacement 5.9 days

NJR achievements and developments during 2006/07

Recorded 131,378 hip and knee joint replacement operations, 81% of the amount undertaken in NHS and independent healthcare units in England and Wales, bringing the total recorded on the Registry to 433,319.

Increased the number of records with patient consent to personal information being included on the Registry, from 78% in 2005 to 83% in 2006.

Increased the number of records with both patient consent and the patient's NHS number, from 58% (shown in NJR 3rd Annual Report) to 69%.

Data capture improvements

Increased direct, on-site support for individual hospitals and treatment centres to help set up or improve processes for submitting information.

Gaining retrospective exemption from the Health and Social Care Act 2001, Section 60, which restricted use of the personal details of patients for whom a response of 'don't know' had been allocated in the records.

Patients being asked for consent to provide their personal details to the NJR at the same time as giving their consent to undergo surgery.