Summary

Demographic and radiological factors significantly influence High Tibial Osteotomy (HTO) outcomes in medial knee osteoarthritis, with Closing Wedge HTO showing higher survivorship compared to Opening Wedge HTO.

Abstract

Background

High tibial osteotomy (HTO) is a proven joint preserving treatment in patients affected by medial compartment osteoarthritis (OA) and varus knee. The goal of HTO is to delay or avoid joint replacement procedures, relieving pain and correct malalignment. To improve effectiveness of HTO a patient personalized approach is required. Therefore, a deep insight in predictive demographical and radiological factors might help highlighting a surgical algorithm to select the best treatment for the specific patients. The aim of the present study was to evaluate demographical and radiological risk factors predictive of failure and to detect differences among two different techniques of valgus-producing HTO.

Methods

a retrospective analysis of patients who underwent isolated Opening (OW) or Closing Wedge (CW) HTO for medial OA in varus knee between 2007 and 2021 in the same institution was performed. Inclusion criteria were fully available clinical records, pre-operative full-length x-ray available and follow-up of at least 2 years. Surgical failure was defined as conversion to total knee arthroplasty (TKA), or need for HTO revision procedure for varus recurrence. Statistical analysis was performed via Kaplan Meier survivorship analysis and univariate analysis using surgical failure as endpoint and demographics and radiological risk factors as independent variables. The demographical parameters assessed included sex, age, BMI, smoking habits and previous meniscectomy. The radiological parameters assessed included HKA (hip-knee angle), MPTA (medial proximal tibial angle), LDFA (lateral distal femoral angle), JLCA (joint line convergency angle) and KL (Kellgren-Lawrence index). Survivorship and univariate analysis were then repeated dividing the population into two subgroups, identified by the surgical technique performed (OW or CW).

Results

131 knees (mean age 43.0 years) were included, with a mean follow up of 9.5±4.2 years. A failure rate of 12.9% (17/131) was recorded, with a survivorship from surgical failure of 87.7% and 78.5% at 10 and 15 years of follow up, respectively. Univariate analysis found several statistically relevant factors in the global population: previous meniscectomy (p=.0061), BMI (p=.0341), LDFA (p=.0458), MPTA (p=.0246) and KL index (p=.0075). Dividing the population into the two subgroups 83 CW and 48 OW were identified, with a failure rate of 10.8% (9/83) and 16.6% (8/48) respectively: statistical relevance was found in survival curves comparison (p=.0120). In CW population univariate analysis showed statistical relevance of smoking habits (P=0,0024), LDFA (P=0,0143) and KL index (P=0,0238), while in OW population only previous meniscectomy was found relevant (P=0.0121).

Conclusion

Demographical and radiological factors influenced survivorship from surgical failure, as well as the surgical technique performed, with higher survivorship of CWHTO population. Previous meniscectomy, BMI, LDFA and KL index were found statistically relevant in the overall population, while smoking habits, LDFA and KL index were significant in CW population and previous meniscectomy in OW population. Our results should be taken into account while planning HTO surgery, matching them with patient’s specific characteristics.