Effect of Surgeon Volume on Mechanical Complications after Resection Arthroplasty with Articulating Spacer

Abstract

Two-stage revision with an antibiotic-loaded cement articulating spacer is a standard treatment for chronic prosthetic knee infection (PKI); however, mechanical complications can occur during the spacer period. There is limited evidence on the association between surgeon volume and mechanical complications after resection arthroplasty (RA) using an articulating spacer. This study aimed to compare the rates of mechanical complications and reoperation after RA with articulating spacers by surgeons with high volumes (HV) and low volumes (LV) of RA performed and analyzed the risk factors for mechanical failure. The retrospective study investigated 203 patients treated with PKIs who underwent RA with articulating spacers and were divided according to the number of RAs performed by the surgeons: HV (≥14 RAs/year) or LV (<14 RAs/year). Rates of mechanical complications and reoperations were compared. Risk factors for mechanical complications were analyzed. Of the 203 patients, 105 and 98 were treated by two HV and six LV surgeons, respectively. The mechanical complication rate was lower in HV surgeons (3.8%) than in LV surgeons (36.7%) (p < 0.001). The reoperation rate for mechanical complications was lower in HV surgeons (0.9%) than in LV surgeons (24.5%) (p < 0.001). Additionally, 47.2% of patients required hinge knees after mechanical spacer failure. Medial proximal tibial angle < 87°, recurvatum angle > 5°, and the use of a tibial spacer without a cement stem extension were risk factors for mechanical complications. Based on these findings, we made the following three conclusions: (1) HV surgeons had a lower rate of mechanical complications and reoperation than LV surgeons; (2) mechanical complications increased the level of constraint in final revision knee arthroplasty; and (3) all surgeons should avoid tibial spacer varus malalignment and recurvatum deformity and always use a cement stem extension with a tibial spacer.

Keywords: articulating spacer; high volume; low volume; mechanical complications; prosthetic knee infection; resection arthroplasty.

Figure 1

Radiographs of the articulating spacer obtained 1 week after resection arthroplasty: (A) standing anteroposterior view; (B) standing lateral view; (C) merchant view; and (D) scanogram of the lower limb.

Figure 2

Malalignment and malposition of articulating spacer: (A) medial distal femoral angle, 100°; (B) medial proximal tibial angle, 83°; (C) posterior tibial slope angle, 96°; (D) flexion contracture, 26°; (E) recurvatum deformity, 11°; (F) femoral spacer notching (arrowhead); (G) medial overhang of tibial spacer (arrowhead); (H) anterior overhang of tibial spacer (arrowhead); (I) femoral spacer without cement stem extension (arrowhead); (J) tibial spacer without cement stem extension (arrowhead); (K) severe varus deformity with hip–knee–ankle angle, 16°; and (L) maltracking with lateral patellar tilt, 14°.

Figure 3

Strengthening the Reporting of Observational Studies in Epidemiology flowchart detailing the design of the study. PKIs, prosthetic knee infections; TKA, total knee arthroplasty; HV, high volume; LV, low volume.

Figure 4

Examples of mechanical complication: (A) a 68-year-old man after resection arthroplasty (RA) with varus malalignment of tibial spacer (medial proximal tibial angle, 83°); (B) periprosthetic tibial fracture (arrowhead) 3 weeks after spacer insertion; (C) reoperation with tibial spacer exchange; (D) a 63-year-old man after RA with recurvatum deformity (12°); (E) femoral spacer fracture (arrowhead) 4 weeks after spacer insertion; (F) reoperation with both spacers exchange; (G) a 76-year-old woman after RA with tibial spacer without cement stem extension; (H) tibial spacer migration (arrowhead) 6 weeks after spacer insertion; and (I) unexpected early reimplantation smoothly.