10 YEAR FOLLOW UP OF ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION IN 30 PATIENTS USING SPECT BONE SCANNING

Abstract

The incidence of osteoarthritis (OA) after an ACL reconstruction is not clear. Reports estimate between 12% and 61% at 8 years post ACL reconstruction. Single Photon emission Computed Tomography (SPECT) scanning (a 3 dimensional radionuclide bone scan) is a sensitive and quantitative method of assessing knee OA, with abnormalities appearing before plain xray and arthroscopic changes.

Aim: to objectively assess the long term result of ACL reconstruction using SPECT.

Method: we have prospectively studied a series of 31 patients (mean age at injury of 29 years) up to a mean follow up of 10 years after ACL reconstruction. None had chondral defects, 15 had meniscectomies at or before ACL reconstruction. Each patient was assessed at 8 – 13 years following ACL reconstruction with clinical examination, plain xrays (grading OA in 3 compartments as 0,1,2 according to Albach) and a SPECT scan (grading metabolic activity as in 3 compartments: 0 (normal); 1 (increased but not clinically significant); 2 (increased, clinically significant); 3 (marked increased activity). The other, normal knee was used as a control.

Results: 43% of those with intact menisci had bone scans suggestive of OA. The prevalence of OA was 87% if meniscectomy was performed. All had a negative pivot shift. The mean Lysholm score was 93 (maximum 100) and the mean Tegner activity score was 6. Only 13% of our patients had clinical symptoms of knee OA.

Conclusions: We found bone scan to be a very sensitive investigation for knee OA, picking up abnormalities suggestive of OA in 66% of patients, with only 13% having clinical symptoms. 10 years post ACL reconstruction with intact menisci, and good clinical results, OA is present on bone scanning in 43%. This doubles if meniscectomy was performed. We encourage other units to use SPECT radionuclide bone scanning as an objective test of the outcome of ACL reconstruction.