Total knee arthroplasty post-high tibial osteotomy, results of an early experience from a North African arthroplasty unit, and a comprehensive review of the literature

Abstract

Purpose: To report an early experience after converting HTO to TKA by reporting the incidence of functional, radiological, and complications in a single surgeon case series from a North African specialized arthroplasty unit.

Methods: Between 2010 and 2020, 33 knees in 31 patients (two bilateral) were operated upon, 24 females and seven males, had a mean age of 65 ± 4.5 years; 17 (51.5%) knees had medial wedge opening (WMO), while 16 (48.5%) had lateral wedge closure (LWC) osteotomies. The mean time from HTO to TKA was 8.1 ± 3.3 years. A posterior stabilized (PS) implant was used in 31 (93.9%), while in 2 (6.1%), a varus-valgus constrained (VVC) implant was used. A tibial stem was needed in 13 (39.4%) knees. The functional assessment was performed according to the Knee Society Scoring System (KSS). The radiographic assessment included the anatomical femorotibial angle (aFTA) for alignment, the medial proximal tibial angle (MPTA), and the tibial slope (TS).

Results: After a mean follow-up of 4.3 ± 1.1 years, the KSS knee and function sub-scores improved from a preoperative mean of 41 ± 8.9 (26 to 57) and 37.7 ± 9.2 (25 to 55) points to 91.3 ± 3.8 (81 to 94) and 85.5 ± 5 (80 to 95) points at the last follow-up, respectively (P < 0.05). The preoperative knee flexion improved from a mean of 84.5° ± 15.9 (55 to 110) to 110.6° ± 9.3 (95 to 125) (P < 0.05). The aFTA improved from a preoperative mean of 182.2° ± 10.3 (164 to 205) to a postoperative mean of 186° ± 2.6 (179 to 190) (P < 0.05). The MPTA changed from a preoperative mean of 88.4° ± 6.7 (77 to 102) to a postoperative (tibial component alignment) mean of 90° ± 1.7 (85 to 94) (P < 0.05). The mean preoperative TS changed from 80.9° ± 7.3 (68 to 96) to a mean postoperative of 86.9° ± 1.3 (83 to 89) (P < 0.05). Non-progressive radiolucent lines were detected at the tibial component in four (12%) knees. Complications were reported in seven (21.2%) knees; no revision was needed in any knee.

Conclusions: The authors' early experience showed improved functional and radiological outcomes; however, the complication incidence was relatively high, but no knees required revision. A longer follow-up is mandatory to prove the consistency of the results.

Keywords: Conversion; High tibial osteotomy; North African; Total knee arthroplasty.

Fig. 1

Female patient, 68 years old. A MWOHTO performed in 2006 using a medial wedge plate. B immediate postoperative after conversion to TKA using a PS implant in January 2013. C Follow-up in August 2015. D Last follow-up (after having a contralateral TKA) in August 2018 (five years follow-up), showing proper implant positioning with no loosening. E Clinical images at the last follow-up showed full knee flexion and extension

Fig. 2

Female patient, 62 years old. A Bilateral LWCHTO (right in 2003 and left in 2004) using a non-locked T-plate (the plate on the right side was removed in a prior session, and the united HTO is shown (yellow arrowhead)). B Bilateral TKA was performed at the same session in 2014, using a PS implant and tibial stem bilaterally. C At six months follow-up, the clinical images showed optimum knee flexion and extension and good healing of the skin incision (red arrowheads showing TKA skin incision, white arrowheads showing the previous HTO skin incision). D At five years follow-up, both knees showed proper implant positioning and no loosening

Fig. 3

Female patient, 65 years old. A LWCHTO performed in 2005 using a long non-locked T-plate. B Immediate postoperative after conversion to TKA using a PS implant in May 2016. C Last follow-up in September 2020, showing proper implant positioning with no loosening

Fig. 4

Male patient, 59 years old. A MWOHTO performed in 2014 using a locked T-plate, preoperative radiographs showed signs of nonunion (red arrowhead). B Intraoperative images while the knee was approached through a medial parapatellar approach, showing the extent of the medial plate. C Immediate postoperative after conversion to TKA using a PS implant and a tibial stem in February 2017. D After three years of follow-up, although the medial HTO gap did not fully unite, the implants showed preserved proper positioning

Fig. 5

Female patient, 61 years old. A LWOHTO performed in 2004 using a non-locked T-plate. B Immediate postoperative after conversion to TKA in March 2015, broken proximal screws were retained, which did not interfere with the tibial component keel. C Last follow-up in August 2020, showing proper implant positioning with no loosening