Distinct Risk Profiles After Conversion Total Knee Arthroplasty: Prior High Tibial Osteotomy Versus Unicompartmental Knee Arthroplasty.

BACKGROUND

Conversion to total knee arthroplasty (TKA) following prior knee procedures such as unicompartmental knee arthroplasty (UKA) or high tibial osteotomy (HTO) is increasingly common. Outcomes may differ between these groups due to variation in patient demographics, comorbidities, and mechanical alterations introduced by the initial surgery. This study compared demographic characteristics and implant-related complications following conversion TKA after UKA or HTO using a large national database.

METHODS

Using a large national database (2010 to 2022), patients who underwent conversion TKA after prior UKA or HTO were identified. Baseline demographics and comorbidities were compared. Implant-related complications at two years, including periprosthetic joint infection, periprosthetic fracture, aseptic loosening, manipulation under anesthesia, and all-cause revision, were analyzed. A total of 6,278 patients were included: 5,884 who had a prior UKA and 394 who had a prior HTO. The HTO patients were significantly younger (45.8 versus 7.1% ≤ 54 years) and had higher rates of alcohol use disorder, drug abuse, and depression, while UKA patients demonstrated higher rates of hypertension and obesity. Logistic regression models adjusted for age, sex, and comorbidities. Odds ratios (OR) with 95% confidence intervals (CI) were calculated, with P < 0.05 considered significant.

RESULTS

At two years, HTO patients had higher rates of manipulation under anesthesia (6.85 versus 3.64%; OR 1.95; 95% CI 1.29 to 2.95; P = 0.002) and all-cause revision (5.84 versus 3.79%; OR 1.57; 95% CI 1.01 to 2.45; P = 0.043). Rates of infection, aseptic loosening, and periprosthetic fracture were similar between groups (all P > 0.05).

CONCLUSIONS

Patients undergoing TKA after HTO represent a younger, comorbid population with distinct psychosocial risk factors. Recognition of these risks may guide counseling, perioperative optimization, and rehabilitation planning.

LEVEL OF EVIDENCE: III.