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Research Article

Time-dependent improvement in functional outcome following LCS rotating platform knee replacement

A prospective longitudinal study in 50 patients

, , , &
Pages 727-732 | Received 10 Dec 2009, Accepted 24 Jul 2010, Published online: 11 Nov 2010
 

Abstract

Background and purpose Long-term follow-up studies after total knee replacement (TKR) using an LCS rotating platform have shown survival rates of up to 97%. Few studies have evaluated short-term functional outcome and its improvement over time. We determined the time course of functional outcome as evaluated by the knee injury and osteoarthritis outcome score (KOOS) over the first 4 years after TKR using the LCS mobile bearing.

Patients and methods 50 unselected patients (mean age 70 (40–85) years, 33 women) with osteoarthritis in one knee underwent TKR with an LCS mobile bearing. Data were collected by an independent investigator preoperatively and at 6 weeks, 3 months, 6 months, 1 year, 2 years and 4 years postoperatively. KOOS, a self-assessment function score validated for this purpose, and range of motion (ROM) were determined at all follow-ups.

Results The mean KOOS pain score increased from 43 before surgery to 66 at 6 weeks and 88 at 2 years. It was 84 at 4 years. The mean KOOS activities of daily living score (ADL) increased from 49 before surgery to 73 at 6 weeks, then gradually to 90 at 2 years. It decreased to 79 at 4 years. Mean passive ROM was 112° before surgery, 78° at departure from hospital, and then gradually increased to 116° at 2 years and 113° at 4 years.

Interpretation Recovery after TKR is time-dependent. Most of the expected improvement in pain and function is achieved at 6 months postoperatively, but some further improvement can be expected up to 2 years postoperatively. ROM will also gradually improve up to 2 years after TKR, and reach the same level as before surgery.

TKN: study design, collection of data, analysis and interpretation of the data, and writing and editing of the manuscript. SH: study design, analysis and interpretation of data, and editing of the manuscript. ET: collection of data and editing of the manuscript. JEM: analysis and interpretation of data and editing of the manuscript. AE: study design, analysis and interpretation of data, and editing of the manuscript.

We are grateful to Dr Nina Gunnes of the Epidemiology Division, Department of Genes and Environment, Norwegian Institute of Public Health, for invaluable help with the statistical analysis.

No competing interests declared.