[BTB allograft for revision surgery of the anterior cruciate ligament - part 2].

PURPOSE OF THE STUDY: The study evaluates our experience with revision anterior cruciate ligament (ACL) surgery, with emphasis placed on the use of allografts.

MATERIAL: In the 2002-2004 period, 421 reconstructions of the anterior cruciate ligament, using patellar BTB or hamstring tendon autografts, were carried out in our orthopedic ward. In the same period we performed 24 revision ACL reconstructions (6 %) with BTB allografts; 19 were in men and five in women. Revision surgery after ACL reconstruction with a BTB graft fixed with a non-absorbable interference screw and with a hamstring tendon graft was performed in 18 and 5 patients, respectively.

METHODS: We distinguish four steps in the revision procedure: 1) diagnosis and analysis of the ACL reconstruction failure; 2) preoperative planning and surgery timing (one- or two-stage procedure, graft type, fixation method); 3) operative procedure; 4) postoperative care including rehabilitation. Revision surgery is indicated on the basis of subjective complaints (instability), and the results of clinical examination (Lachman's and pivot-shift tests) and imaging methods (X-ray, MRI, arthroscopy). Causes of failure are categorized as 1) traumatic (major trauma, too early weight-bearing, minor trauma due to rehabilitation); 2) surgery-related (erroneous position of the tibial and/or femoral tunnels, insufficient tensioning of the graft and its insufficient fixation); 3) biological (poor ;graft incorporation and restructuring, infection); and 4) combination of all previous causes. Errors in tunnel position are differentiated according to the part of the tunnel (tibial, femoral or both) tunnel direction (ventral, dorsal, lateral or medial) and the degree of malposition (mild, moderate or serious). We perform one-stage surgery when the position of tunnels is correct, with the exception of revision due to infection, and in all malpositions but for a dorsally positioned tibial tunnel. In a moderate degree of femoral tunnel ventral malposition, we make decisions individually. A two-stage procedure consists of removal of the failed graft and fixation material and spongioplasty followed by revision surgery. The results of revision reconstruction greatly depend on a correct isometric position. We extend the tunnel, if it is in a mild-degree malposition, and create a new, smaller tunnel, if the malposition is severe. Fixation, with either the Rigidfix system or interference screws, is also selected according to the direction and degree of malposition. In the last 3 years, we used exclusively grafts harvested from cadavers.

RESULTS: In the group of 24 patients undergoing revision ACL reconstruction, the right knee was treated in 13. The previous ACL reconstruction was done with BTB grafts in 18 patients, with hamstring tendons in 5 patients and one patient underwent reconstruction by Harnach's method in an outside institution. The average time between the primary reconstruction and revision surgery was 27 months (range, 4 to 169 months). We found a surgery-associated error in 12 cases. poor graft restructuring in 3 and involvement of traumatic etiology in 11 cases. One patient underwent revision surgery because of infection. We used one-stage procedures in 20 patients and two-stage procedures in four patients. We fixed the graft with femoral interference screws and the Rigidfix system in 17 and 7 patients, respectively, and with tibial interference screws in 23 patients (absorbable screw completed with cancellous screw in one patient). Only in one patient did we use the tibial Rigidfix system. The average follow-up was 16 months. No infection, thromboembolic disease or synovialitis were recorded. One patient experienced a recurrent failure of the graft and one patient was treated for the Cyclops lesion. The average Lysholm scores were 78.25 (range, 48-97); 87.5 % of the patients were satisfied with the results and the same proportion of patients would undergo the surgery again. The overall results appeared poorer due to the patients in whom revision ACL reconstruction was performed on arthritic joints.

DISCUSSION: The outcomes of revision surgery are worse than those in primary reconstruction. We regard allografts with massive bony blocks, adjusted as required, as an optimal method. The risk of disease transmission is low, operative time is shorter, incision is smaller and further trauma to the treated or the other, healthy knee due to graft harvest is avoided. Only patients without signs of gonarthrosis who have motivation are indicated for revision surgery, because they can be expected to cooperate well in the postoperative period.

CONCLUSIONS: Revision ACL surgery should be performed by surgical teams with sufficient experience in this field. The crucial point is the analysis of ACL reconstruction failure with further procedure planning. The use of BTB allografts from the local tissue bank proved efficient in our hospital. In the hands of experienced surgeons, allograft offer great prospects for ACL reconstruction with good outcome.