J-bone graft with double locking plate: a symphony of mechanics and biology for atrophic distal femoral non-union with bone defect

OBJECTIVE: Atrophic distal femur non-union with bone defect (ADFNBD) has been a worldwide challenge to treat due to the associated biological and mechanical problems. The purpose of this study was to introduce a new solution involving the use of a J-shaped iliac crest bone graft (J-bone) combined with double-plate (DP) in the treatment of femoral non-union. METHODS: Clinically, 18 patients with ADFNBD were included in this retrospective study and were treated with a combination of J-bone graft and DP. The average follow-up time was 22.1 ± 5.5 months (range, 14 to 34 months). The imaging information and knee joint activity tests and scores were used to evaluate the time to weight-bearing, the time to non-union healing, and the knee joint mobility. A finite element analysis was used to evaluate the differences between the following: (1) the use of a lateral locking plate (LLP) only group (LLP-only), (2) a DP only group (DP-only), (3) a DP with a J-bone group (DP+J-bone), and (4) an LLP with a J-bone group (LLP+J-bone) in the treatment of ADFNBD. A finite element analysis ABAQUS 6.14 (Dassault systems, USA) was used to simulate the von Mises stress distribution and model displacement of the plate during standing and normal walking. RESULT: All patients with non-union and bone defect in the distal femur achieved bone healing at an average of 22.1 ± 5.5 months (range, 14 to 34 months) postoperatively. The average healing time was 6.72 ± 2.80 months. The knee Lysholm score was significantly improved compared with that before surgery. Under both 750 N and 1800 N axial stress, the maximum stress with the DP+J-bone structure was less than that of the LLP+J-bone and DP-only structures, and the maximum stress of J-bone in the DP+J-bone was significantly less than that of the LLP+J-bone+on structure. The fracture displacement of the DP+J-bone structure was also smaller than that of the LLP+J-bone and DP-only structures. CONCLUSION: J-bone combined with DP resulted in less maximum stress and less displacement than did a J-bone combined with an LLP or a DP-only graft for the treatment of ADFNBD. This procedure was associated with less surgical trauma, early rehabilitation exercise after surgery, a high bone healing rate, and a satisfactory rate of functional recovery. Therefore, a combination of J-bone and DP is an effective and important choice for the treatment of ADFNBD.