Biomechanical analysis of tension band wiring （TBW） of transverse fractures of patella

Purpose： Tension band wiring is commonly used for fixation of simple transverse fractures. The popular configuration is parallel Kirschner wires （K-wires） and a stainless steel wire loop placed in a vertically oriented figure-of-8. Methods： We used a wooden model of a patella with a midway transverse fracture and compared four different types of fixation. The first construct had a vertical figure-of-8 with one twist of wire. The second contained a vertical figure-of-8 with two twists of wire. The third was a vertical figure-of-8 with two twists of wire placed at adjacent corners while the last one had a horizontal figure-of-8 with two twists of wire placed at adjacent corners, lnterfragmentary compression at the point of wire breakage was measured for each construct as well as permanent displacement on cyclic loading. Results： Placement of the figure-of-eight in a horizontal orientation with two wire twists at the corner improved interfragmentary compression by 63% （p 〈 0.05, Tukey post ]hoc test）. On cyclic loading, all the constructs with vertical figure-of-eight but none with a horizontal construct failed （p = 0.01; Fisher＇s exact test）. Permanent fracture displacement after cyclic loading was ,57% lower with horizontal figure- of-eight constructs （p 〈 0.05; t test）. Conclusion： Placing wire twists at the corner and a horizontal placement of figure-of-8 improves stability of the construct.

A Double Tension Band Technique for Patellar Fractures—A New Concept

Amongst the many known techniques used for the management of fractures of the patella, the tension band wire fixation is a reliable treatment modality and has given consistently good results. In transverse patellar fractures, a combination of cerclage wiring and tension band fixation gives a good mechanical stability and an environment conducive to healing. The fracture described herein is classified as 45-C1 (based on Orthopaedic Trauma Association classification) of the right knee of a forty three years old male patient. It was fixed with three vertical 1.5 mm K wires and double cerclage wire looped proximally through the quadriceps tendon and distally through the patellar ligament in a double figure-of-eight configuration. The average follow-up period was 7 months. The Activity of Daily Living Scale (ADLS) of the Knee Outcome Survey was used to assess symptoms and functional capability of the knee. The fracture union was achieved at an average of 10 weeks. Full range of knee motion was achieved by end of the third postoperative month. No complications, such as infection and implant failure were noted. The technique aims to stress the advantage of giving a balanced fixation addressing the bony elements (the fractured ends) as well as the soft tissue (the extensor apparatus).

Comparison of the clinical efficacy of different fixation systems for the treatment of transverse patellar fractures

Purpose:This study was designed to compare the clinical efficacy of"8"and"0"wire fixation systems combined with double-head cannulated compression screws or Kirschner wires for the treatment of transverse patellar fractures.Methods:From September 2011 to September 2018,patients with closed transverse patellar fractures treated with a double-head compression screw or Kirschner wire were included and analyzed retrospectively.Patients with patellar fractures combined with distal femoral fractures,tibial plateau fracture or preoperative lower limb dysfunction were excluded.The patients treated with the"8"tension band wire fixation system and Kirschner wire were taken as Group A;those treated with the"0"fixation system and Kirschner wire were taken as Group B;those treated with the"8"fixation system and double-head cannulated compression screw were taken as group C;and those treated with the"0"fixation system and double-head cannulated compression screw were taken as group D.Six weeks and one year after the operation and every month from the third month after the operation until the fractures healed,an X-ray examination was performed to identify fracture healing.The time of fracture healing and postoperative complications of the four groups were compared.One year after the operation,knee function was evaluated by Bostman’s score.Results:During the study period,168 patients with patellar fractures were treated by operations,and 88 patients were excluded because the fracture type did not meet the requirements or because there were combined fractures of the distal femur or tibial plateau.As a result,80 patients were included in this study,20 in each group.All the patients were followed up for an average period of 12.2 months.Compared with Group A,patients in Group D presented less postoperative discomfort in the prepatellar region,quicker fracture healing,less fixation failure and better postoperative knee function scores(all p<0.05).The incidence of internal fixation failure in Group(B+D)was lower than that in Group(A+C)(p>0.05).Conclusion:The"0"wire fixation system combined with a double-head cannulated compression screw seems to be more beneficial than the other three fixation systems for the treatment of transverse patellar fractures.