Fibular Notch Technique in Total Ankle Replacements for Externally Rotated Ankles Shontal Behan Dionisopoulos, DPM1; Megan A. Ishibashi DPM1; John M. Schuberth, DPM2 1 Chief Residents, Kaiser San Francisco Bay Area Foot and Ankle Residency Program – Oakland, CA, 3 Attending Surgeon, Kaiser Permanente San Francisco – San Francisco, CA

Purpose Case Study Analysis & Discussion

The current recommendation for 53 patients with externally rotated ankles who Arthritic ankles with an externally rotated transmalleolar axis require placement of a total ankle prosthesis in underwent a primary TAR were included in this internal rotation of the tibial tray to approximate the line of progression. the transverse plane is to approximate study. A fibular notch was performed on all patients When this is done, the effective width of the ankle mortise decreases. As the transmalleolar axis. However, a large at time of implant. Patients had an average follow up such, seating of the tibial tray is precluded because of the medial-lateral proportion of patients with end stage of 7 years. . dimension of the tibial tray. The fibular notch technique allows the arthritis present with an exaggerated implant to be placed parallel to the line of progression, and effectively externally rotated transmalleolar axis due Technique & Procedures: Fibular notch decompresses the gutters. Malalignment of TAR implant, especially in to external torque from gait alteration or technique Standard anterior ankle dissection is the axial plane of the tibial component, is associated with gutter a neglected or malunited fibula.1 performed exposing a 180-degree horizon of the impingement and potentially, a gutter debridement. In our case series, Placement in an exaggerated rotation ankle. The long alignment guide is then attached to none of the patients required a subsequent debridement. Similar results can lead to increased gutter the proximal tibia with a pin, allowing the were recognized by Nejefi et al. who found that by respecting the impingement and poor mechanics. The appropriately sized cutting block to be positioned transmalleolar axis for implant placement, their rate of medial purpose of this study is to evaluate the over the center of the ankle as directed by the impingement decreased to 1.9%, which is exceptionally lower than the efficacy of fibular notching to decrease manufacturing implant guide. The cutting block is 7% quoted in literature.1,3,4 the incidence of gutter impingement. internally rotated to approximate the line of progression (Figure 1). The fibular notch is The effects of malrotation in total knee arthroplasties has been Figure 1: Internal rotation of cutting block to Figure 2: Intraoperative fluoroscopy demonstrating the completed by resecting approximately one-third to fibular notch - resection of approximately one-third of the extensively studied. It has been shown that malrotation of the tibial approximate the line of progression medial distal fibula. one-half of the medial distal fibula (Figure 2). We component leads to increased contact stresses, specifically on the recommend utilizing a reciprocating saw from distal extensor mechanism.5,6 The ankle has an even smaller surface area for Literature Review to proximal, starting at the tip of fibula and ending at load transduction and subtle variations in translation or congruency of the transverse cut across the tibia and fibula. Again, the articulating surface has been shown to have significant impact on this ensures that there will be enough room for 7 Insertion of a TAR implant usually contact pressures. In fact, any type of malpositioning of total ankle proper implant rotation and positioning in the axial 8 involves the use of an extramedullary implants has been shown to lead to premature polyethylene wear. Thus, plane. Finally, the talus will need to be mobilized to rod which determines the frontal plane there is comparable potential that malrotated total ankle implants can allow for complete frontal and transverse reduction. position of the tibial tray. Transverse also result in rotational torque opposing the malrotation of the implant, The talus should then be sized and prepared in plane position of the tray and talar potentially resulting in premature polyethylene wear or component sequential fashion according to the standard 9 component is determined by the medial loosening. manufacturer protocol. Following successful gutter line. However, there is a large placement of prosthesis (Figure 3), a non-weight variation between the medial gutter line References bearing short leg splint should be applied for two and the transmalleolar axis.2 Addressing weeks, followed by 4 weeks in a short leg walking 1. Najefi AA, Ghani Y, Goldberg A. Role of Rotation in Total Ankle Replacement. Foot Ankle Int. 2019 Dec;40(12):1358-1367. the rotation, or axial plane, of the 2. Schuberth JM, Wood DA, Christensen JC. Gutter Impingement in Total Ankle Arthroplasty. Foot Ankle Spec. 2016 Apr;9(2):145-58. cast. At 6 weeks postoperative, the patient can be 3. Schuberth JM, Babu NS, Richey JM, Christensen JC. Gutter impingement after total ankle arthroplasty. Foot Ankle Int. 2013 Mar;34(3):329- prosthesis is important because 37. transitioned to weightbearing as tolerated to a 4. Rippstein PF, Huber M, Naal FD. Management of specific complications related to total ankle arthroplasty. Foot Ankle Clin. 2012 malrotation can lead to poor mechanics Dec;17(4):707-17. boot/shoe. 5. D'Lima DD, Chen PC, Colwell CW Jr. Polyethylene contact stresses, articular congruity, and knee alignment. Clin Orthop Relat Res. 2001 and gutter impingement. Our case series Nov;(392):232-8. 6. Matsuda S, White SE, Williams VG 2nd, McCarthy DS, Whiteside LA. Contact stress analysis in meniscal bearing total knee arthroplasty. J provides a technique to adequately Arthroplasty. 1998 Sep;13(6):699-706. Results: To date, with annual follow ups, zero 7. Pyevich MT, Saltzman CL, Callaghan JJ, Alvine FG. Total ankle arthroplasty: a unique design. Two to twelve-year follow-up. J Bone Joint prepare the ankle for appropriate Surg Am. 1998 Oct;80(10):1410-20. patients have required subsequent gutter 8. Espinosa N, Walti M, Favre P, Snedeker JG. Misalignment of total ankle components can induce high joint contact pressures. J Bone Joint alignment of the TAR implant. Surg Am. 2010 May;92(5):1179-87. doi: 10.2106/JBJS.I.00287. debridement (Figure 4). Figure 3: Implant in appropriate axial alignment in an Figure 4: Anteroposterior radiograph of patient at 7 year 9. Fukuda T, Haddad SL, Ren Y, Zhang LQ. Impact of talar component rotation on contact pressure after total ankle arthroplasty: a cadaveric externally rotated ankle. follow-up with no medial or lateral gutter impingement. study. Foot Ankle Int. 2010 May;31(5):404-11.