Under-corrected knees do not fail more than aligned knees at 8 years in fixed severe valgus total knee replacement
- 148 Downloads
A fixed severe valgus knee is a surgical challenge. A safe post-operative Hip-Knee-Ankle angle (HKA) range of 180° ± 4 was recommended, but recent studies mentioned equal results from outliers of this range. Nevertheless, no distinction was made between varus and valgus knees, as well as over-corrected or under-corrected knees. Did post-operative nonaligned total knee replacements (TKR) from fixed severe valgus knees behave differently from the properly aligned population? Did over-corrected knees behave differently from under-corrected knees?
Through a multi-center retrospective cohort study, we provided 557 knees of at least 10° of minimal pre-operative valgus; in this population 75 presented a post-operative Hip-Knee-Ankle angle (HKA) outside of the 180° ± 4 range; 23 of them had at least 5° of varus; 52 of them had at least 5° of valgus. Median pre-operative HKA of the entire cohort was 194° (range 190–198). Median follow-up was 8 years (range 5–11); Knee Society Score (KSS) results, HKA, Femoral and Tibial Mechanical Angles (FMA, TMA) and complication rates were obtained. The outlier group (HKA ≤ 175 or ≥ 185) was compared to the control group (HKA 180 ± 4); over-corrected (HKA ≤ 175) and under-corrected (HKA ≥ 185) sub-groups were individually tested against the control group.
The outlier group had a lower Final Knee Score than the aligned group (p = 0.023). In the over-corrected sub-group, median post-operative FMA was 88° (SD 4°) and median TMA was 87° (SD 4°). The complication rate was higher (p = 0.019). Knee (p = 0.018), Function (p = 0.034) and Final Knee Scores (p = 0.03) were statistically lower than in the control group. In the under-corrected sub-group, mean post-operative FMA was 93° (SD 2°) and mean TMA was 91° (SD 2°). The complication rate was lower (p = 0.019) and there was no difference with the control group concerning KSS.
In case of pre-operative fixed severe valgus knee, one should avoid over-correcting HKA angle and especially the TMA. Over-correction of a severe preoperative valgus in a post-operative varus was prejudicial for TKA survival. Keeping a severe valgus knee in low valgus to avoid using a more constrained implant and/or ligament releases will not decrease the 5–10 year implant survival and functional scores.
Level of evidence
Level IV—Case series.
KeywordsValgus deformity Knee arthritis Total knee arthroplasty Residual deformity
No funding was necessary for this study.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
French Orthopedic Society SOFCOT does not require an ethical approval statement for inhouse studies.
- 9.Huang T-W, Chuang P-Y, Lee C-Y, Lin S-J, Huang K-C, Shen S-H, Tsai Y-H, Lee MS, Hsu RW-W (2016) Total knee arthroplasty in patients with Ranawat type-II valgus arthritic knee with a marked coronal femoral bowing deformity: comparison between computer-assisted surgery and intra-articular resection. J Orthop Surg 11:88CrossRefGoogle Scholar
- 10.Insall J, Ranawat CS, Scott WN, Walker P (1976) Total condylar knee replacment: preliminary report. Clin Orthop Relat Res 120:149–154Google Scholar
- 11.Insall JN, Dorr LD, Scott RD, Scott WN (1989) Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res 248:13–14Google Scholar
- 12.Keblish PA (1991) The lateral approach to the valgus knee. Surgical technique and analysis of 53 cases with over two-year follow-up evaluation. Clin Orthop Relat Res 271:52–62Google Scholar
- 14.Krackow KA, Jones MM, Teeny SM, Hungerford DS (1991) Primary total knee arthroplasty in patients with fixed valgus deformity. Clin Orthop Relat Res 273:9–18Google Scholar
- 15.Lombardi AV, Berend KR, Ng VY (2011) Neutral mechanical alignment: a requirement for successful TKA: affirms. Orthopedics 34:504–506Google Scholar
- 19.Mont MA, Mahoney OM (2010) Commentary on an Article by Sebastien Parratte, MD., PhD et al.: “Effect of postoperative mechanical axis alignment on the fifteen-year survival of modern, cemented total knee replacements”. J Bone Joint Surg 92-A:e16(1)–e16(2)Google Scholar
- 32.Whiteside LA (1993) Correction of ligament and bone defects in total arthroplasty of the severely valgus knee. Clin Orthop Relat Res 288:234–245Google Scholar