ABSTRACT
Hoffa fractures are intra-articular fractures of the distal femoral condyles in coronal plane. These fractures may be of either condylebut lateral condyle is most commonly affected and medial condyle is extremely rare. Non-operative treatment of unicondylarfemur fractures, including Hoffa fractures, yields poor result. We present a case of 9-year-old child with Hoffa fracture of medialfemoral condyle with understanding of the mechanism of injury and its further management. He had history of fall from height ofabout 5 feet on his right knee which was in flexed position at around 90°. X-ray of knee showed fracture of medial femoral condylein coronal plane. Three-dimensional (3D) reconstruction of computed tomography (CT) scan confirmed the coronal fracture ofmedial femoral condyle and was classified as Type 33 B3 according to orthopedic trauma association classification and Type 1as per Letenneur classification. Open reduction and internal fixation were performed with partially threaded cancellous screws.The fixation of coronal fracture of medial femoral condyle done through cancellous screws in anterior to posterior direction wasadequate in giving stable fixation and aided in union without disturbing the physis of the child. At 1 year, the child could do fullextension and 130° flexion. There was no posterior or varus, valgus instability of the knee. We believe that a medial condyleHoffa fracture is extremely rare in children, and the diagnosis can be missed. ORIF using partially threaded cancellous screwsin the epiphysis provides stable fixation and can lead to a good functional outcome in the long term. The mechanism of injuryin this fracture pattern was found to be direct impact on the knee in flexed position of 90°.
ABSTRACT
HLA-B*4006 is the most common allele amongst Indians. It belongs to the ‘HLA-B44 supertype’ family of alleles that constitute an important component of the peptide binding repertoire in populations world over. Its peptide binding characteristics remain poorly examined. The amino acid sequence and structural considerations suggest a small, poorly hydrophobic ‘F’ pocket for this allele that may adversely affect the interaction with the C terminal residue of the antigenic peptide. Contribution of auxiliary anchor residues (P3) of the peptide has also been indicated. To examine these aspects by in silico analysis, HLA-B*4001, 4002, and 4006 alleles were modeled using HLA-B*4402 as a template. Eleven peptides, known to bind alleles of this family, were used for docking and molecular dynamics studies. Interaction between the amino group (main-chain) of P3 residue and Tyr99 of the alleles was seen in majority of peptide-complexes. Hydrophobic interactions between Tyr7 and Tyr159 with N terminal residues of the peptide were also seen in all the complexes. Replacement of Trp95 by leucine in HLA-B*4006 resulted in reduction of binding free energy in 8 out of 9 complexes. In summary, the analysis of the modeled structures and HLA-peptide complexes strongly supports the adverse effect of Trp95 at pocket F and the possible role of the third residue of the antigenic peptide as an auxiliary anchor in HLA-B*4006 peptide complexes. In the light of suggested promiscuous peptide binding pattern and association with risk for tuberculosis/HIV for this allele, the ascertainment of the predicted effects of Trp95 and role of P3 residue as an auxiliary anchor by this preliminary in silico analysis thus helps define direction of the further studies.