Sang Jun Song

Objectives: To evaluate patient reference in paired bilateral posterior stabilized (PS) total knee arthroplasties (TKAs) with significantly different degrees of joint line obliquity (JLO) change. Methods: A retrospective review was conducted on 128 patients who underwent paired bilateral PS TKAs, with greater and smaller JLO changes (G-ΔJLO and S-ΔJLO knees; a side-to-side difference in JLO change >3° between G-ΔJLO and S-ΔJLO knees). The mean follow-up period was 3.9 years (minimum 2 years). Radiographic changes in JLO were measured according to the Coronal Plane Alignment of the Knee (CPAK) classification. Maintenance of the CPAK type and JLO direction (apex distal, neutral, and apex proximal) was investigated. Clinically, the preferred TKA out of greater and smaller JLO changes was investigated. The Hospital for Special Surgery and Western Ontario and McMaster Universities Osteoarthritis Index were evaluated. Results: The average JLO change was 10.5° in the G-ΔJLO knees and 5.5° in the S-ΔJLO knees (p < 0.001). The CPAK type and JLO direction was better maintained in the S-ΔJLO knees (p < 0.001, respectively). Regarding preference, 40 patients (31.2%) were satisfied with bilateral TKAs without a specific preference, while 44 patients (34.3%) preferred TKAs of the G-ΔJLO knee and 44 patients (34.3%) preferred the S-ΔJLO knee (p = 1.000). No significant differences were found in the patient reported outcomes between the G- and S-ΔJLO knees. Conclusions: The degree of joint line obliquity change was not associated with patient preference in bilateral PS TKAs. JLO preservation may not be a critical determinant of patient preference in PS TKA.

Purpose: To analyze the correlation and degree of agreement between the patellar heights measured at knee flexion of 0° and 30° before and after total knee arthroplasties (TKA) without patellar resurfacing. Methods: One hundred primary TKAs with nonresurfaced patella were prospectively evaluated. We measured the Insall–Salvati ratio (ISR), modified ISR (mISR), Blackburne-Peel ratio (BPR), and Caton-Deschamps ratio (CDR) in weightbearing true lateral radiograph at knee flexion of 0° and 30°. The correlations between the patellar height measured at knee flexion of 0° and 30° were analyzed by Pearson correlation analysis. The degree of agreement between the patellar heights in knee flexion angles of 0° and 30° was analyzed using the limits of agreement (LoA) of Bland–Altman analysis; a difference of < ± 0.2 between the measurements at knee flexion of 0° and 30° was deemed clinically acceptable. Results: Very strong correlations existed between the pre- and postoperative ISR (r = 0.826 and 0.823, p < 0.001, respectively), and the preoperative mISR (r = 0.802, p < 0.001) measured between knee flexion angles of 0° and 30°. Strong correlation was observed in the other pre- and postoperative measurements. The range between upper and lower LoAs of the ISR measured at knee flexion of 0° and 30° was < ± 0.20 preoperatively (−0.174 ~ 0.155) and postoperatively (−0.181 ~ 0.174), while the ranges for all other measurements did not lie within the clinically acceptable range. Conclusions: The ISR measured at 0° or 30° of knee flexion during weightbearing can be interchanged reasonably before and after TKA. Although knee flexion of 30° is the standard, lateral radiograph of 0° flexion can be a reasonable alternative for evaluating patellar height using the ISR. Level of Evidence: Level II.

Background/Objectives: This Phase 3, randomised, double-blind, multicentre trial evaluated the efficacy and safety of a novel hyaluronic acid hydrogel cross-linked with hexamethylenediamine (HMDA-HA) compared to a conventional 1,4-butanediol diglycidyl ether cross-linked HA (BDDE-HA) in patients with mild-to-moderate knee osteoarthritis (OA). Methods: A total of 223 adults (mean age 63.5 years; 167 women) with Kellgren–Lawrence (KL) grade I–III knee OA were randomised 1:1 to receive two intra-articular injections of HMDA-HA or BDDE-HA at baseline and at 24 weeks. The primary endpoint was changes from baseline in weight-bearing pain (WBP) on a 100 mm visual analogue scale (VAS) at Week 12, assessed in the per-protocol population. A non-inferiority margin of 10 mm was predefined. Secondary outcomes included global assessments, Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index scores, responder rates, and rescue medication use [ClinicalTrials.gov: NCT06307847]. Results: At Week 12, least squares mean change (standard error [SE]) in WBP was −23.72 (1.88) mm in the HMDA-HA group (n = 83) and −25.99 (1.76) mm in the BDDE-HA group (n = 95), yielding a difference of 2.26 mm (95% confidence interval [CI]: −2.83 to 7.34; p = 0.3825), thus demonstrating the non-inferiority of HMDA-HA to BDDE-HA. Secondary outcomes were comparable between groups. A total of 136 adverse events were reported: 44 (41.1%) in the HMDA-HA group and 32 (28.1%) in the BDDE-HA group, with no treatment-related adverse drug reactions. Conclusions: A single-injection intra-articular regimen of HMDA-HA was effective and safe for the treatment of adult patients with mild-to-moderate knee OA.

Song SJ, et al. Clin Orthop Surg. 2022 Nov;14:e95. https://doi.org/10.4055/cios22207

Song SJ, et al. Clin Orthop Surg. 2022 Apr;14:e27. https://doi.org/10.4055/cios21154

Purpose The study aims to analyze long-term clinical and radiographic results, and survival of re-revision total knee arthroplasty (TKA) using fully cemented stems performed on femurs with diaphyseal deformation. Methods Thirty-seven re-revision TKAs using fully cemented stems performed in femoral diaphyseal deformations, characterized as diaphyseal canal enlargement and cortex deformation due to aseptic loosening of previously implanted stems, between 2003 and 2015 were retrospectively reviewed. The mean follow-up period was 10.0 years. Clinically, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and range of motion (ROM) were evaluated. Radiographically, mechanical axis (MA) and component positions were measured. Complications and survival rates were also analyzed. Results Clinically, the WOMAC significantly improved at final follow-up (61.2 vs 47.2, p < 0.001), but not the ROM (95.5 vs 102.5, p = 0.206). Radiographically, the MA and component positions were appropriate, with no changes in component positions from immediately post-operative to final follow-up, but with MA change from varus 2.9° to 3.7° (p = 0.020). Two cases (5.4%) with history of previous infections developed periprosthetic joint infection (PJI). Debridement with polyethylene insert exchange following antibiotic suppression were performed in those cases because of concern for difficult implant-cement removal. The five and ten year survival rates were 100% and 93.2%, respectively. Conclusion Fully cemented stems are viable in providing long-term satisfactory survival after re-revision TKA in patients with femoral diaphyseal deformation. However, it should be used carefully for those with previous infections.