The Bridging Technique Of Allograft Plates Of Cortex For Femoral Revision With Severe Bone Defects

[BACKGROUND]With the artificial joint being widely used clinically ,the number of revision gradually increased accordingly. In the year of 2000,183000 cases of total hip arthroplasties (THA) were performed in USA, including 31000 revision operations, accounting for 17% or so. Comparing to primary THA, revision operation was more difficulty, more skill-demanded and really the big challenge for the orthopedic surgeon. If the bone defects of femur was reconstructed conventionally, there were many limitations such as the amount and intensity of autograft bone. In the situation, it was put forward that the bone defects of femur can be repaired with the bridging technique of allograft plates of cortex. [OBJECTIVES]From 2000 the follow up were carried out on the cases with severe bone defects of femur being repaired with the bridging technique of allograft plates of cortex so as to evaluate feasibility and effectiveness of this technique in hip revision and the advantages and principle of this technique. [METHOD]From 2000 to 2005,15 cases (male 8,female 7) with severe bone defects of femur beingrepaired with the bridging technique of allograft plates of cortex were followed up clinically and radiologically. The average age was 66 (48-77).The average time from primary THA to revision was 9.27 years (3-16 years). The lateral approach was used in 3 cases and posterolateral approach in 15 cases. According to AAOS classification, 15 hips belonged to type II (4 cases) , type III (8 cases) and type IV (3 cases) respectively and at the same time 13 cases had the acetabuiar bone defects. The average Harris score was 47 (20-73) preoperatively. The extended approach were used in all cases. The biological femoral implants were used in 12 hips and cemented implants in 3 hips. At the same time the acetabuiar intervention was carried out in 13 hips ,4 cases of which were reconstructed with titanium mesh and constructive bone grafting. The bone defect was supported with single allograft plate of cortex in 12 hips, two allograft plate of cortex in 3 hips. No external fixation was needed in all cases postoperatively. [RESULTS]The average follow up time was 26 months (10-60).The follow up contents included symptoms and signs, the walking gait and radiology. The average postoperative Harris score was 72 (59-89) ,25 up comparing to that preoperatively. 13 cases could walk for the long distance with single stick and 2 cases with single shoulder stick. Radiologically, all the allograft plates of cortex bridged with the trabeculae of host bone and bone healing happened. The average healing time was 15 months (10-25). No complications such as infection, fracture of allograft plates of cortex, nonunion and absorb of allograft plates of cortex occurred in the all cases. [CONCLUSION]The bridging technique of allograft plates of cortex in repairing the severe bone defects of femur is feasible and at least get good effects clinically and radiologically. The advantages of the technique is to offer the support biomechanically, to restore the bone amount in the femoral side, to give attachment bed for the soft tissue and to facilitate the restoration of hip function. The principle of the technique is as follows. The allograft plates of cortex should be modified so as to make sure there is the biggest cover area between allograft plates of cortex and host bone. The autograft in the reaming femur and rasping the acetabuiar should be collected and used for press-fit of bone grafting in interval between allograft plates of cortex and host bone. The host periosteum should be protected and excessive removal of the surrounding soft tissue should be avoided. The leakage of cement between allograft plates of cortex and host bone should beavoided . The reaming of femur should be performed gradually from the small size to the big oneand intensified imaging is used if necessary.