Distal Femoral Valgus Resection Angle in Conventional Total Knee Arthroplasty - a CT Scanogram Study

Document Type : RESEARCH PAPER

Authors

Department of Orthopedics, Sagar Hospitals , Bangalore, India

Abstract

Objectives: In conventional total knee arthroplasty (TKA), the distal femur valgus resection angle (DFVA) is decided 
either by measuring the specific resection angle for each patient on preoperative anteroposterior hip-knee-ankle 
(HKA) weight-bearing radiograph or using a fixed resection angle of five to seven degrees, when such facilities are 
not available. This study aims to measure the DVFA in TKA patients using preoperative HKA non-weight-bearing 
computerized tomography (CT) scanogram scout films and determine its relation with preoperative coronal plane 
lower-limb deformities.
Methods: In this retrospective radiological study, various measurements were performed on bilateral, preoperative 
hip-knee-ankle CT scanograms of 73 knee osteoarthritis patients who had presented for total knee replacement 
surgery using a standard protocol. The angle between the femoral anatomical axis and femoral mechanical axis 
was measured as the femoral mechanical anatomical angle (FMAA), which corresponds to the surgical DFVA. The 
angle between the femoral and tibial mechanical axes was measured as mechanical femorotibial angle (MFTA). 
The correlation between FMAA and MFTA was studied.
Results: The mean FMAA for the study group was 6.45° (range 3° to 11°, SD 1.17°). The MFTA for the study group 
ranged from 24° varus to 14° valgus. The alignment was valgus in 14.4% (n=21), varus in 84.2% (n=123), and “0 
degrees” in 1.3% (n=2). With valgus coronal alignment taken as positive and varus as negative, the Pearson's 
correlation coefficient for MFTA with FMAA was r = −0.5183 (p<0.001), indicating that valgus knees tended to have 
a smaller FMA angle and varus knees tended to have a larger FMA angle.
Conclusion: In the non-availability of individualized measurements, in primary TKA, we recommend setting DFVA 
as five degrees for valgus deformities, six degrees for mild/moderate varus deformities (MFTA <15°) and seven 
degrees for severe varus deformities (MFTA > 15°).
 Level of evidence: III

Keywords

Main Subjects


  1. Sharkey PF, Hozack WJ, Rothman RH, Shastri S, Jacoby SM. Insall Award paper. Why are total knee arthroplasties failing today? Clin Orthop Relat Res. 2002 ;( 404):7-13. doi:10.1097/00003086-200211000-00003
  2. Lotke PA, Ecker ML. Influence of positioning of prosthesis in total knee replacement. J Bone Joint Surg Am. 1977; 59(1):77-79.
  3. Fang DM, Ritter MA, Davis KE. Coronal alignment in total knee arthroplasty: just how important is it? J Arthroplasty. 2009; 24(6 Suppl):39-43. doi:10.1016/j.arth.2009.04.034
  4. Jeffery RS, Morris RW, Denham RA. Coronal alignment after total knee replacement. J Bone Joint Surg Br. 1991; 73(5):709-714. doi:10.1302/0301-620X.73B5.1894655
  5. Parratte S, Pagnano MW, Trousdale RT, Berry DJ. Effect of postoperative mechanical axis alignment on the fifteen-year survival of modern, cemented total knee replacements. J Bone Joint Surg Am. 2010; 92(12):2143-2149. doi:10.2106/JBJS.I.01398
  6. Lombardi AV Jr, Berend KR, Ng VY. Neutral mechanical alignment: a requirement for successful TKA: affirms. Orthopedics. 2011; 34(9):e504-e506. doi:10.3928/01477447-20110714-40
  7. Choong PF, Dowsey MM, Stoney JD. Does accurate anatomical alignment result in better function and quality of life? Comparing conventional and computer-assisted total knee arthroplasty. J Arthroplasty. 2009; 24(4):560-569. doi:10.1016/j.arth.2008.02.018
  8. Bargren JH, Blaha JD, Freeman MA. Alignment in total knee arthroplasty. Correlated biomechanical and clinical observations. Clin Orthop Relat Res. 1983 ;( 173):178-183.
  9. Matziolis G, Adam J, Perka C. Varus malalignment has no influence on clinical outcome in midterm follow-up after total knee replacement. Arch Orthop Trauma Surg. 2010; 130(12):1487-1491. doi:10.1007/s00402-010-1064-9
  10. Bellemans J. Neutral mechanical alignment: a requirement for successful TKA: opposes. Orthopedics. 2011; 34(9):e507-e509. doi:10.3928/01477447-20110714-41
  11. Mohanlal P, Jain S. Assessment and validation of CT scanogram to compare per-operative and post-operative mechanical axis after navigated total knee replacement. Int Orthop. 2009; 33(2):437-439. doi:10.1007/s00264-008-0639-3
  12. Bäthis H, Perlick L, Tingart M, Lüring C, Zurakowski D, Grifka J. Alignment in total knee arthroplasty. A comparison of computer-assisted surgery with the conventional technique. J Bone Joint Surg Br. 2004; 86(5):682-687. doi:10.1302/0301-620x.86b5.14927
  13. Thienpont E, Fennema P, Price A. Can technology improve alignment during knee arthroplasty? Knee. 2013; 20 Suppl 1:S21-S28. doi:10.1016/S0968-0160(13)70005-X
  14. Kharwadkar N, Kent RE, Sharara KH, Naique S. 5 degrees to 6 degrees of distal femoral cut for uncomplicated primary total knee arthroplasty: is it safe? Knee. 2006; 13(1):57-60. doi:10.1016/j.knee.2005.07.001
  15. Costa MA, Mozella Ade P, Cobra HA. Distal femoral cut in total knee arthroplasty in a Brazilian population. Rev Bras Ortop. 2015; 50(3):295-299. doi:10.1016/j.rboe.2015.05.007
  16. Bardakos N, Cil A, Thompson B, Stocks G. Mechanical axis cannot be restored in total knee arthroplasty with a fixed valgus resection angle: a radiographic study. J Arthroplasty. 2007; 22(6 Suppl 2):85-89. doi:10.1016/j.arth.2007.04.018
  17. Palanisami D, Iyyampillai G, Shanmugam S, Natesan R, S R. Individualised distal femoral cut improves femoral component placement and limb alignment during total knee replacement in knees with moderate and severe varus deformity. Int Orthop. 2016; 40(10):2049-2054. doi:10.1007/s00264-016-3123-5
  18. Lee CY, Huang TW, Peng KT, Lee MS, Hsu RW, Shen WJ. Variability of distal femoral valgus resection angle in patients with end-stage osteoarthritis and genu varum deformity: Radiographic study in an ethnic Asian population. Biomed J. 2015; 38(4):350-355. doi:10.4103/2319-4170.151030
  19. Hsu RW, Himeno S, Coventry MB, Chao EY. Normal axial alignment of the lower extremity and load-bearing distribution at the knee. Clin Orthop Relat Res. 1990 ;( 255):215-227.
  20. Tang WM, Zhu YH, Chiu KY. Axial alignment of the lower extremity in Chinese adults. J Bone Joint Surg Am. 2000; 82(11):1603-1608. doi:10.2106/00004623-200011000-00014
  21. Farrar MJ, Newman RJ, Mawhinney RR, King R. Computed tomography scan scout film for measurement of femoral axis in knee replacement. J Arthroplasty. 1999; 14(8):1030-1031. doi:10.1016/s0883-5403(99)90021-9
  22. Henckel J, Richards R, Lozhkin K, et al. Very low-dose computed tomography for planning and outcome measurement in knee replacement. The imperial knee protocol. J Bone Joint Surg Br. 2006; 88(11):1513-1518. doi:10.1302/0301-620X.88B11.17986
  23. Mullaji AB, Shetty GM, Kanna R, Vadapalli RC. The influence of preoperative deformity on valgus correction angle: an analysis of 503 total knee arthroplasties. J Arthroplasty. 2013; 28(1):20-27. doi:10.1016/j.arth.2012.04.014
  24. Mose K. Methods of measuring in Legg-Calvé-Perthes disease with special regard to the prognosis. Clin Orthop Relat Res. 1980 ;( 150):103-109.

25       Abdel MP, Oussedik S, Parratte S, Lustig S, Haddad FS. Coronal alignment in total knee replacement: historical review, contemporary analysis, and future direction. Bone Joint J. 2014; 96-B (7):857-862. doi:10.1302/0301-620X.96B7.33946.

26      Jingjit W, Poomcharoen P, Limmahakhun S, Klunklin K, Leerapun T, Rojanasthien S. Femoral mechanical-anatomical angle of osteoarthritic knees. J Med Assoc Thai. 2014; 97(12):1314-1318.

27.      Rezende FC, de Castro Ferreira M, Debieux P, da Silveira Franciozi CE, Luzo MVM, Carneiro M. Is it safe the empirical distal femoral resection angle of 5° to 6° of valgus in the Brazilian geriatric population? Rev Bras Ortop. 2013; 

48(5):421-426. doi:10.1016/j.

 

rboe.2012.08.009

  1. Curtin B, Fehring TK, Lauber J. Errors in knee alignment using fixed femoral resection angles. Orthopedics. 2014; 37(7):e644-e648. doi:10.3928/01477447-20140626-56
  2. Meric G, Gracitelli GC, Aram LJ, Swank ML, Bugbee WD. Variability in Distal Femoral Anatomy in Patients Undergoing Total Knee Arthroplasty: Measurements on 13,546 Computed Tomography Scans. J Arthroplasty. 2015; 30(10):1835-1838. doi:10.1016/j.arth.2015.04.024
  3. Deakin AH, Basanagoudar PL, Nunag P, Johnston AT, Sarungi M. Natural distribution of the femoral mechanical-anatomical angle in an osteoarthritic population and its relevance to total knee arthroplasty. Knee. 2012; 19(2):120-123. doi:10.1016/j.knee.2011.02.001
  4. Brouwer RW, Jakma TS, Bierma-Zeinstra SM, Ginai AZ, Verhaar JA. The whole leg radiograph: standing versus supine for

determining axial alignment. Acta Orthop Scand. 2003; 74(5):565-568. doi:10.1080/00016470310017965

  1. Gbejuade HO, White P, Hassaballa M, Porteous AJ, Robinson JR, Murray JR. Do long leg supine CT scanograms correlate with weight-bearing full-length radiographs to measure lower limb coronal alignment? Knee. 2014; 21(2):549-552. doi:10.1016/j.knee.2013.05.009
  2. Ranawat AS, Ranawat CS, Elkus M, Rasquinha VJ, Rossi R, Babhulkar S. Total knee arthroplasty for severe valgus deformity. J Bone Joint Surg Am. 2005; 87 Suppl 1(Pt 2):271-284. doi:10.2106/JBJS.E.00308
  3. Deakin AH, Sarungi M. A comparison of variable angle versus fixed angle distal femoral resection in primary total knee arthroplasty. J Arthroplasty. 2014; 29(6):1133-1137. doi:10.1016/j.arth.2013.11.009