Achilles tendon allograft reconstruction of the anterior cruciate ligament-deficient knee

Thirty-five patients had reconstruction of the anterior cruciate ligament with intraarticular fresh-frozen Achilles tendon allograft and extraarticular tibial band tenodesis. Patients were followed 2 to 4 years (mean, 2.5). Evaluation included clinical and functional examinations, measurement of tibiofemoral displacement, and anteroposterior and lateral radiographs. Clinical results were considered satisfactory in 85% of the patients; 16 had arthroscopic examination after the allograft; allograft biopsies in 9 at this time showed cellular and vascular tissue without evidence of immune reaction. Clinical, arthroscopic, and biopsy results were favorable, but radiologic results were not. In most patients there was a significant size increase in femoral and tibial bone tunnels, as measured from radiographs. In the 6 most extreme cases, bone tunnels measured 20 mm or more in diameter, twice the initial size. Etiology and clinical significance of these bone tunnel changes remain unknown. Enlargement appears to occur early after operation; it stabilizes within 2 years. No statistical correlation was seen between tunnel enlargement and results of clinical and functional examinations; nevertheless, unexplained tunnel enlargement is cause for concern, and allograft replacement of the anterior cruciate ligament with fresh-frozen Achilles tendon allograft should be considered a salvage procedure.