Radiographic Comparison of the Mechanical Axis Including Calcaneus to the Conventional Mechanical Axis in Medial Unicompartmental Knee Arthroplasty

Abstract

Since a hindfoot alignment is not included in the conventional mechanical axis (hip–ankle [HA] line), a mechanical axis including the calcaneus (hip–calcaneus [HC] line) has recently attracted attention as an alternative weight-bearing line. However, there are few reports on unicompartmental knee arthroplasty (UKA) regarding the HC line. Therefore, this study aimed to compare postoperative alignments after UKA between the HA line and the HC line. Postoperatively, HC radiographs were taken in 88 consecutive patients who underwent medial UKA. The hip–knee–ankle (HKA) and hip–knee–calcaneus (HKC) angles were compared in the same patient. Regarding tibial inclination, the conventional tibial component–ankle (TCA) angle was compared with reference to the HC line (tibial component–calcaneus [TCC] angle). The mean postoperative HKA and HKC angles were 2.8 ± 2.7 and 2.0 ± 2.5 degree, respectively. The mean postoperative TCA and TCC angles were 87.7 ± 2.1 and 88.5 ± 2.1 degree, respectively. There were significant differences between the two groups in both lower limb alignment and tibial component angle. The present study indicated that the HKC and the TCC angles significantly decreased the varus alignment by approximately 1 degree compared with the HKA and TCA angles. Neutral in the HA line corresponds to valgus in reference to the HC line, which may result in overcorrection. Surgeons should consider evaluating the HC line in place of the HA line, which may affect preoperative planning and postoperative outcome during UKA. This is a Level II, diagnostic study.

Keywords

unicompartmental knee arthroplasty - hip–knee–calcaneus angle - mechanical axis - hindfoot alignment

Publication History

Received: 11 July 2019

Accepted: 10 November 2019

Article published online:
30 December 2019

• References

• 1 Berger RA, Meneghini RM, Jacobs JJ. et al. Results of unicompartmental knee arthroplasty at a minimum of ten years of follow-up. J Bone Joint Surg Am 2005; 87 (05) 999-1006
• 2 Murray DW, Goodfellow JW, O'Connor JJ. The Oxford medial unicompartmental arthroplasty: a ten-year survival study. J Bone Joint Surg Br 1998; 80 (06) 983-989
• 3 Whiteside LA. Making your next unicompartmental knee arthroplasty last: three keys to success. J Arthroplasty 2005; 20 (04, Suppl 2): 2-3
• 4 Cooke TD, Scudamore A, Greer W. Varus knee osteoarthritis: whence the varus?. J Rheumatol 2003; 30 (12) 2521-2523
• 5 Mullaji A, Shetty GM. Persistent hindfoot valgus causes lateral deviation of weightbearing axis after total knee arthroplasty. Clin Orthop Relat Res 2011; 469 (04) 1154-1160
• 6 Haraguchi N, Ota K, Tsunoda N, Seike K, Kanetake Y, Tsutaya A. Weight-bearing-line analysis in supramalleolar osteotomy for varus-type osteoarthritis of the ankle. J Bone Joint Surg Am 2015; 97 (04) 333-339
• 7 Matsumoto T, Takayama K, Ishida K, Hayashi S, Hashimoto S, Kuroda R. Radiological and clinical comparison of kinematically versus mechanically aligned total knee arthroplasty. Bone Joint J 2017; 99-B [phone]
• 8 Sawatari T, Tsumura H, Iesaka K, Furushiro Y, Torisu T. Three-dimensional finite element analysis of unicompartmental knee arthroplasty--the influence of tibial component inclination. J Orthop Res 2005; 23 (03) 549-554
• 9 Zambianchi F, Digennaro V, Giorgini A. et al. Surgeon's experience influences UKA survivorship: a comparative study between all-poly and metal back designs. Knee Surg Sports Traumatol Arthrosc 2015; 23 (07) 2074-2080
• 10 Zhu GD, Guo WS, Zhang QD, Liu ZH, Cheng LM. Finite element analysis of mobile-bearing unicompartmental knee arthroplasty: the influence of tibial component coronal alignment. Chin Med J (Engl) 2015; 128 (21) 2873-2878
• 11 Akizuki S, Mueller JK, Horiuchi H, Matsunaga D, Shibakawa A, Komistek RD. In vivo determination of kinematics for subjects having a Zimmer Unicompartmental High Flex Knee System. J Arthroplasty 2009; 24 (06) 963-971
• 12 Tanaka T, Takayama K, Hashimoto S. et al. Radiographic analysis of the lower limbs using the hip-calcaneus line in healthy individuals and in patients with varus knee osteoarthritis. Knee 2017; 24 (05) 1146-1152
• 13 Faul F, Erdfelder E, Buchner A, Lang AG. Statistical power analyses using G*Power 3.1: tests for correlation and regression analyses. Behav Res Methods 2009; 41 (04) 1149-1160
• 14 Reilingh ML, Beimers L, Tuijthof GJ, Stufkens SA, Maas M, van Dijk CN. Measuring hindfoot alignment radiographically: the long axial view is more reliable than the hindfoot alignment view. Skeletal Radiol 2010; 39 (11) 1103-1108
• 15 Chandler JT, Moskal JT. Evaluation of knee and hindfoot alignment before and after total knee arthroplasty: a prospective analysis. J Arthroplasty 2004; 19 (02) 211-216
• 16 Vasso M, Del Regno C, D'Amelio A, Viggiano D, Corona K, Schiavone Panni A. Minor varus alignment provides better results than neutral alignment in medial UKA. Knee 2015; 22 (02) 117-121
• 17 Zuiderbaan HA, van der List JP, Chawla H, Khamaisy S, Thein R, Pearle AD. Predictors of subjective outcome after medial unicompartmental knee arthroplasty. J Arthroplasty 2016; 31 (07) 1453-1458
• 18 Tashiro Y, Matsuda S, Okazaki K, Mizu-Uchi H, Kuwashima U, Iwamoto Y. The coronal alignment after medial unicompartmental knee arthroplasty can be predicted: usefulness of full-length valgus stress radiography for evaluating correctability. Knee Surg Sports Traumatol Arthrosc 2014; 22 (12) 3142-3149
• 19 Chatellard R, Sauleau V, Colmar M, Robert H, Raynaud G, Brilhault J. ; Société d'Orthopédie et de Traumatologie de l'Ouest (SOO). Medial unicompartmental knee arthroplasty: does tibial component position influence clinical outcomes and arthroplasty survival?. Orthop Traumatol Surg Res 2013; 99 (4, Suppl): S219-S225
• 20 Inoue S, Akagi M, Asada S, Mori S, Zaima H, Hashida M. The valgus inclination of the tibial component increases the risk of medial tibial condylar fractures in unicompartmental knee arthroplasty. J Arthroplasty 2016; 31 (09) 2025-2030
• 21 Kamenaga T, Hiranaka T, Hida Y, Fujishiro T, Okamoto K. Effect of tibial component position on short-term clinical outcome in Oxford mobile bearing unicompartmental knee arthroplasty. J Orthop Sci 2018; 23 (05) 807-810
• 22 Dai X, Fang J, Jiang L, Xiong Y, Zhang M, Zhu S. How does the inclination of the tibial component matter? A three-dimensional finite element analysis of medial mobile-bearing unicompartmental arthroplasty. Knee 2018; 25 (03) 434-444
• 23 Boonen B, Kerens B, Schotanus MG, Emans P, Jong B, Kort NP. Inter-observer reliability of measurements performed on digital long-leg standing radiographs and assessment of validity compared to 3D CT-scan. Knee 2016; 23 (01) 20-24