Subsidence Starts Distally: Scaffolding Versus Reconstitution Closure of the Extended Trochanteric Osteotomy in Revision Total Hip Arthroplasty.

Abstract

Extended trochanteric osteotomy (ETO) facilitates safe removal of well-fixed femoral stems during revision total hip arthroplasty (rTHA). The optimal ETO closure method, scaffolding (open ETO during canal preparation) or reconstitution (ETO reduced prior to preparation), remains unclear, especially regarding subsidence of tapered splined titanium stems (TSTS). We evaluated the impact of the ETO closure technique on postoperative TSTS subsidence, hypothesizing no significant difference. We retrospectively reviewed 66 rTHAs (2016 to 2020) performed with ETO and TSTS implantation. There were 35 cases that used reconstitution and 31 that used scaffolding. Subsidence was measured radiographically from immediate postoperative to final follow-up. Subsidence greater than five mm was deemed clinically relevant. Statistical analyses included Mann-Whitney U-tests, Chi-square tests, and multivariable logistic regressions. Average subsidence was higher in the reconstitution group (6.0 ± 3.6 mm) than in the scaffolding group (4.3 ± 2.9 mm, P = 0.018). Rates of significant subsidence (greater than five mm) were similar (31.4 versus 32.3%, P = 0.958). Scaffolding achieved greater distal bicortical contact (50 ± 5.4 versus 28 ± 4.8 mm; P = 0.002), which inversely correlated with subsidence (r = -0.26, P = 0.037). Contact length within the ETO was not predictive of subsidence (P = 0.359). Logistic regression identified distal bicortical contact greater than 30 mm below the ETO as protective against significant subsidence (odds ratio (OR) 0.12, P < 0.001). Subgroup analysis revealed lower subsidence in reconstitution cases with a healed ETO (e.g., staged periprosthetic joint infection revisions) than in fresh ETOs closed with reconstitution (4.0 ± 1.1 versus 9.1 ± 2.4 mm). The ETO union rates were high (94.0%) in both groups. Both closure techniques are viable; however, scaffolding offers superior distal fixation and reduced subsidence in fresh osteotomies. Reconstitution yields similar outcomes when the ETO is healed. Ensuring greater than 30 mm of bicortical contact below the ETO is key to minimizing stem subsidence, regardless of closure technique.