Medial UKA tends to increase patellar height, whereas open-wedge HTO tends to decrease patellar height

Main Article Content

Mo Saffarini, MEng, MBA, FRMS Philippe Alves Julien Billieres Robin Martin


Background: There is no consensus on the most appropriate method to assess patellar height following medial unicompartmental arthroplasty (UKA) or open-wedge high tibial osteotomy (HTO). The purpose of this study was to evaluate the difference between pre- and post-operative patellar height in patients receiving UKA or HTO using three indices of patellar height.

Methods: The authors retrospectively analysed pre- and post-operative radiographs of 44 patients that received medial UKA (n=21) or open-wedge HTO (n=23). Pre- and post-operative radiographs were standardised between patients, including anterior-posterior, and lateral in 30° flexion images. Postoperative radiographs were obtained at 6 weeks. Patellar height was assessed according to the Insall-Salvati index, Blackburne-Peel index, and Caton-Deschamps index.

Results: Patients that received UKA (67.4±5.8 years) were significantly older than patients that received HTO (51.3±9.0 years, p<0.001). Preoperative patellar height was similar between patients that received UKA or HTO according to all three indices. Postoperative patellar height was similar among the two groups according to the Insall-Salvati index, but was significantly greater following UKA according to the Blackburne-Peel index (0.95±0.13 vs. 0.75±0.24, p=0.003) and Caton-Deschamps index (1.09±0.17 vs. 0.93±0.26, p=0.019). According to all three indices, UKA tended to increase patellar height, whereas HTO tended to decrease patellar height. The differences between pre- and post-operative patellar heights were however not significant, except for the Caton-Deschamps index following UKA (p=0.043).

Conclusion: According to all three indices, medial UKA tended to increase patellar height, whereas open-wedge HTO tended to decrease patellar height.  

Article Details

How to Cite
SAFFARINI, Mo et al. Medial UKA tends to increase patellar height, whereas open-wedge HTO tends to decrease patellar height. Medical Research Archives, [S.l.], v. 8, n. 9, sep. 2020. ISSN 2375-1924. Available at: <>. Date accessed: 27 oct. 2020. doi:


1. Anagnostakos K, Lorbach O, Kohn D (2012) Patella baja after unicompartmental knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 20 (8):1456-1462.
2. Behrendt C, Zaluski A, RP EA, de Sousa EB, Cavanellas N (2016) Comparative evaluation of patellar height methods in the Brazilian population. Rev Bras Ortop 51 (1):53-57.
3. Bin SI, Kim HJ, Ahn HS, Rim DS, Lee DH (2016) Changes in Patellar Height After Opening Wedge and Closing Wedge High Tibial Osteotomy: A Meta-analysis. Arthroscopy 32 (11):2393-2400.
4. Blackburne JS, Peel TE (1977) A new method of measuring patellar height. J Bone Joint Surg Br 59 (2):241-242.
5. Bonadio MB, Torres JA, Mazzaro V, Jr., Helito CP, Gobbi RG, Demange MK (2016) PLATEAU-PATELLA ANGLE: AN OPTION FOR ASSESSING PATELLAR HEIGHT ON PROXIMAL TIBIA OSTEOTOMY. Acta Ortop Bras 24 (3):127-130.
6. Brouwer RW, Bierma-Zeinstra SM, van Koeveringe AJ, Verhaar JA (2005) Patellar height and the inclination of the tibial plateau after high tibial osteotomy. The open versus the closed-wedge technique. J Bone Joint Surg Br 87 (9):1227-1232.
7. Cao Z, Mai X, Wang J, Feng E, Huang Y (2018) Unicompartmental Knee Arthroplasty vs High Tibial Osteotomy for Knee Osteoarthritis: A Systematic Review and Meta-Analysis. J Arthroplasty 33 (3):952-959.
8. Caton J, Deschamps G, Chambat P (1982) Patellae inferae. Rev Chir Orthop Reparatrice Appar Mot 68 (5):317-325.
9. Chae DJ, Shetty GM, Lee DB, Choi HW, Han SB, Nha KW (2008) Tibial slope and patellar height after opening wedge high tibia osteotomy using autologous tricortical iliac bone graft. Knee 15 (2):128-133.
10. Davies GS, van Duren B, Shorthose M, Roberts PG, Morley JR, Monk AP, Murray DW, Pandit HG (2016) Changes in patella tendon length over 5 years after different types of knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 24 (9):3029-3035.
11. Gaasbeek RD, Nicolaas L, Rijnberg WJ, van Loon CJ, van Kampen A (2010) Correction accuracy and collateral laxity in open versus closed wedge high tibial osteotomy. A one-year randomised controlled study. Int Orthop 34 (2):201-207.
12. Grelsamer RP, Meadows S (1992) The modified Insall-Salvati ratio for assessment of patellar height. Clin Orthop Relat Res (282):170-176.
13. Insall J, Salvati E (1971) Patella position in the normal knee joint. Radiology 101 (1):101-104.
14. Insall J, Walker P (1976) Unicondylar knee replacement. Clin Orthop Relat Res (120):83-85.
15. Kaper BP, Bourne RB, Rorabeck CH, Macdonald SJ (2001) Patellar infera after high tibial osteotomy. J Arthroplasty 16 (2):168-173.
16. Kozinn SC, Marx C, Scott RD (1989) Unicompartmental knee arthroplasty. A 4.5-6-year follow-up study with a metal-backed tibial component. J Arthroplasty 4 Suppl:S1-10.
17. Lee OS, Ahn S, Lee YS (2018) Changes of Sagittal and Axial Alignments of Patella after Open- and Closed-Wedge High-Tibial Osteotomy: A Systematic Review and Meta-Analysis. J Knee Surg 31 (7):625-634.
18. Lobenhoffer P, Agneskirchner JD (2003) Improvements in surgical technique of valgus high tibial osteotomy. Knee Surg Sports Traumatol Arthrosc 11 (3):132-138.
19. Naal FD, Neuerburg C, von Knoch F, Salzmann GM, Kriner M, Munzinger U (2009) Patellar height before and after unicompartmental knee arthroplasty: association with early clinical outcome? Arch Orthop Trauma Surg 129 (4):541-547.
20. Neogi DS, Bae JH, Seok CW, Lim HC (2014) Impact of patellar height on unicompartment knee arthroplasty: does patella baja lead to an inferior outcome? J Orthop Traumatol 15 (1):47-54.
21. Phillips CL, Silver DA, Schranz PJ, Mandalia V (2010) The measurement of patellar height: a review of the methods of imaging. J Bone Joint Surg Br 92 (8):1045-1053.
22. Rogers BA, Thornton-Bott P, Cannon SR, Briggs TW (2006) Interobserver variation in the measurement of patellar height after total knee arthroplasty. J Bone Joint Surg Br 88 (4):484-488.
23. Seil R, Muller B, Georg T, Kohn D, Rupp S (2000) Reliability and interobserver variability in radiological patellar height ratios. Knee Surg Sports Traumatol Arthrosc 8 (4):231-236.
24. Staubli AE, De Simoni C, Babst R, Lobenhoffer P (2003) TomoFix: a new LCP-concept for open wedge osteotomy of the medial proximal tibia--early results in 92 cases. Injury 34 Suppl 2:B55-62.
25. van Duijvenbode D, Stavenuiter M, Burger B, van Dijke C, Spermon J, Hoozemans M (2016) The reliability of four widely used patellar height ratios. Int Orthop 40 (3):493-497.
26. Verhulst FV, van Sambeeck JDP, Olthuis GS, van der Ree J, Koeter S (2019) Patellar height measurements: Insall-Salvati ratio is most reliable method. Knee Surg Sports Traumatol Arthrosc 10.1007/s00167-019-05531-1.
27. Weale AE, Murray DW, Newman JH, Ackroyd CE (1999) The length of the patellar tendon after unicompartmental and total knee replacement. J Bone Joint Surg Br 81 (5):790-795.
28. Wiley AM (1967) Reconstruction of the osteoarthritic knee by high tibial osteotomy and joint clearance. Can J Surg 10 (1):28-35.

Most read articles by the same author(s)

Obs.: This plugin requires at least one statistics/report plugin to be enabled. If your statistics plugins provide more than one metric then please also select a main metric on the admin's site settings page and/or on the journal manager's settings pages.