Purpose: The aim of our study was to analyze 20 patients who underwent secondary posterior cruciate ligament (PCL) reconstruction after previous isolated anterior cruciate ligament (ACL) reconstruction had been performed. Our analysis sought to assess ACL graft preservation or failure in these patients. A secondary aim of our study was to identify a testing protocol to be used before any surgery that would help diagnose PCL deficiency and avoid unneeded ACL reconstruction.
Methods: A total of 180 PCL reconstructions were prospectively documented, and 20 patients (11%) were identified who underwent previous isolated ACL reconstruction. Cases were analyzed to determine the quantity of ACL graft failures that had occurred and the need for ACL graft removal due to a fixed posterior subluxation. Patient charts were thoroughly reviewed, so investigators could identify the number of patients with incorrect diagnosis (PCL involvement was overlooked or an intact ACL was replaced) and the number with incorrect management (isolated ACL reconstruction was performed even though PCL involvement was recognized).
Results: A fixed posterior subluxation was present in 4 cases; this necessitated subsequent ACL graft resection in 2 patients to release subluxation prior to PCL reconstruction. In all, 7 ACL grafts failed because of overlooked posterolateral instability. In only 11 of 20 cases, the initial ACL graft could be preserved. ACL reconstruction was performed because of incorrect diagnosis in 16 patients and incorrect management in 4.
Conclusions: A considerably high number of overlooked or underestimated PCL injuries led to isolated ACL reconstruction, which indicates that diagnostic difficulties still occur among orthopaedic surgeons who are not highly specialized. Beside persistent posterior laxity, a failed ACL graft was the main reason for a second operation, which required bicruciate ligament reconstruction. To avoid incorrect management and incorrect diagnosis, leading to isolated ACL reconstruction in PCL deficiency, we recommend that stress radiography be performed to detect eventual posterior instability.
Level of evidence: Level IV, therapeutic case series.