Abstract
Statement of purpose
To analyse the distribution of osteoarthritis of the knee, to determine what proportion of patients may be suitable for a partial knee replacement and finally to assess the risk of wear progression.
Summary of methods used and results
The intra-operative articular surface mappings were collected for 250 consecutive patients undergoing knee arthroscopy. Patients were graded using the Outerbridge Classification. Radiographs including antero-posterior standing, postero-anterior flexion (Rosenberg), lateral and skyline views were graded (Kellgren and Lawrence) and compared with the arthroscopic findings.
13.3% of knees showed ‘isolated’ medial disease of Outerbridge Grade 3 or worse. Isolated lateral disease was noted in 1.4%, patello-femoral disease in 24.3%, bi-compartmental (Medial/PFJ) disease in 30.9% with tibio-femoral and tri-compartmental disease in 15.2%. The combination of lateral and patello-femoral disease was seen in 14.8%.
The mean age of patients with tri-compartmental disease (60.9 years) was greater than the mean age of those suffering with osteoarthritis limited to one or two compartments (54 years)
Radiological analysis revealed AP views had only 66% sensitivity and 73% specificity for the presence of Grade 3/4 lesions in the medial compartment. Rosenberg views had 73% sensitivity and 83% specificity. Skyline views had a sensitivity of 56% and 100% specificity.
Statement of conclusion
The study suggests up to 85% of patients may be suitable for partial knee replacement. The study suggests the number of compartments affected by grade 3 and 4 disease increases with patient age.
A large proportion of patients may be suitable for partial replacements. However, the presence of high levels of Grade 1 and 2 changes found in other compartments indicates a need for caution.
