RESUMEN
Aims: The aims of this study were: 1) to describe extended restricted kinematic alignment (E-rKA), a novel alignment strategy during robotic-assisted total knee arthroplasty (RA-TKA); 2) to compare residual medial compartment tightness following virtual surgical planning during RA-TKA using mechanical alignment (MA) and E-rKA, in the same set of osteoarthritic varus knees; 3) to assess the requirement of soft-tissue releases during RA-TKA using E-rKA; and 4) to compare the accuracy of surgical plan execution between knees managed with adjustments in component positioning alone, and those which require additional soft-tissue releases. Methods: Patients who underwent RA-TKA between January and December 2022 for primary varus osteoarthritis were included. Safe boundaries for E-rKA were defined. Residual medial compartment tightness was compared following virtual surgical planning using E-rKA and MA, in the same set of knees. Soft-tissue releases were documented. Errors in postoperative alignment in relation to planned alignment were compared between patients who did (group A) and did not (group B) require soft-tissue releases. Results: The use of E-rKA helped restore all knees within the predefined boundaries, with appropriate soft-tissue balancing. E-rKA compared with MA resulted in reduced residual medial tightness following surgical planning, in full extension (2.71 mm (SD 1.66) vs 5.16 mm (SD 3.10), respectively; p < 0.001), and 90° of flexion (2.52 mm (SD 1.63) vs 6.27 mm (SD 3.11), respectively; p < 0.001). Among the study population, 156 patients (78%) were managed with minor adjustments in component positioning alone, while 44 (22%) required additional soft-tissue releases. The mean errors in postoperative alignment were 0.53 mm and 0.26 mm among patients in group A and group B, respectively (p = 0.328). Conclusion: E-rKA is an effective and reproducible alignment strategy during RA-TKA, permitting a large proportion of patients to be managed without soft-tissue releases. The execution of minor alterations in component positioning within predefined multiplanar boundaries is a better starting point for gap management than soft-tissue releases.
RESUMEN
BACKGROUND: No scientific evidence exists regarding the amount of bone cement used and discarded in primary cemented Total knee arthroplasty (TKA). The aim of this study was to identify the exact amount of bone cement utilized for component fixation in primary TKA. METHODS: In a prospective study carried out at five centers, 133 primary cemented TKAs were performed. One pack of 40g Palacos bone cement (PBC 40) was hand mixed and digitally applied during the surgery. After fixation of the TKA components, the remaining bone cement was methodically collected and weighed on a digital weighing scale. The actual quantity of cement utilized for component fixation was calculated. RESULTS: On an average, 22.1 g of bone cement was utilized per joint, which accounted to 39 % of 57 g, the solidified dry weight of PBC 40. Among 133 knees, the cement usage was 20 % to 50% in 109 knees, more than 50% in 20 knees and less than 20% in 4 knees. Knees which received larger sized femoral implant required more cement compared to medium and small sizes. Knees which had pulse lavage had more cement utilization compared to knees which had simple syringe lavage before implantation. CONCLUSION: Large quantity of bone cement was handled than actual requirements in primary TKA when a standard 40g pack was used with the digital application technique, resulting in sizeable discard of bone cement. Customizing cement pack according to the implant size can potentially avoid this cement wastage. Future research is required to study the utility and economic impact of smaller packs (20 g or 30 g) of bone cement in primary TKA.