Surgeon-Applied Stress and a Ligament Tensor Instrument Provide a Similar Assessment of Preresection Flexion Laxity During Robotic Total Knee Arthroplasty.

Background: Robotic-assisted total knee arthroplasty (RA-TKA) allows surgeons to perform intraoperative soft tissue laxity assessments prior to bone resections and is used to alter resections to achieve gap balance. This study compared 2 techniques for flexion gap laxity assessment during RA-TKA. Methods: A prospective study of 50 primary RA-TKAs performed by a single surgeon was conducted between February and October 2023. Following full exposure, anterior tibial dislocation, and osteophyte removal, maximal medial and lateral compartment flexion laxity was quantified to the nearest 0.5 mm by the robotic system using a dynamic, surgeon-applied stress (SURGEON). This data was used to plan a balanced flexion gap by adjusting the femoral component size, rotation, and anterior-posterior translation. Flexion laxity was quantified again after distal femoral and proximal tibial resections using a ligament tensor instrument (TENSOR). These new data were used to plan for the same desired flexion gap using the same variables. Paired-samples t-tests and a simple linear regression were used for analysis. Results: Both methods produced near-identical recommendations for femoral component sizing (mean deviation 0.06 sizes, range -1 to +1 size; P = .569), rotation (deviation mean 1.0°, range -3.0° to +3.0°; P = .741), and anterior-posterior translation (deviation mean 0.13 mm, range -0.5 to +0.5 mm, P = .785). SURGEON femoral component rotation predicted TENSOR rotation (R2 = 0.157; 95% confidence interval = 0.124, 0.633; P = .004). Conclusions: Assessing flexion laxity with a surgeon-applied stress vs a ligament tensor produced near-identical laxity data in RA-TKA, suggesting surgeons may comfortably choose either technique as a reliable method. Level of Evidence: Level III.

Midterm results for revision total knee arthroplasty for component malrotation.

INTRODUCTION: Accurate positioning of components in total knee arthroplasty (TKA) is essential to a satisfactory outcome. Significant malrotation may lead to chronic pain, stiffness, and dysfunction. This study aims to quantify improvements in functional outcomes following revision surgery for malrotation of either one or both components in TKA versus revision for aseptic loosening. METHODS: This was a retrospective review of TKAs that matched and compared the two-year functional outcomes of the malrotation group to a functionally similar aseptic loosening group. Functional outcomes were compared between groups using Short Form (SF-12), Western Ontario and McMaster University Osteoarthritis Index (WOMAC), and Knee Society Functional Score (KSFS). Student t-tests and chi-squared or Fisher's tests were used for statistical analysis. RESULTS: Of the patients revised, 24 had malrotation and 57 had aseptic loosening. A total of 16 femoral and 17 tibial components were revised for malrotation. All 16 femoral components were internally malrotated (mean -4.8 ± 4.1 degrees; range, -0.5 to -16.6). Of the tibial components, 15 were internally malrotated, (mean -9.5 ± 6.6 degrees; range, -2.2 to -23.5) and 2 were externally malrotated (mean 4.6 ± 2.1 degrees; range, 3.1 to 6.0). All functional outcome measures significantly improved comparably within both groups preoperatively to 24 months postoperatively. At 24 months, functional outcome measures were comparable between the groups and WOMAC function scores were significantly higher in the malrotation group. CONCLUSION: Revision TKA for malrotation can yield clinically and statistically significant functional improvements, similar in magnitude to those seen following revision TKA for aseptic loosening. LEVEL OF EVIDENCE: Level III.

2-Octyl-Cyanoacrylate Mesh Dressings for Total Joint Arthroplasty: Dressing Design Influences Risks of Wound Complications.

BACKGROUND: Recent liquid adhesive skin closure systems with a mesh patch and a 2-octyl cyanoacrylate liquid formula have shown promising results in total joint arthroplasty. Chemical accelerators are typically included to promote the rapid polymerization of 2-octyl cyanoacrylate. The goal of the study is to distinguish designs and wound complication differences between 2 similar systems. METHODS: An 18-week retrospective study was conducted from July to December 2023, including 207 total hip arthroplasty and 212 total knee arthroplasty cases from 4 attending surgeons at 1 institution that used 1 of 2 dressing designs. Both dressings had a 2-octyl cyanoacrylate liquid adhesive formula that applied topically to a polyester-based mesh overlaying the wound. Mesh A (used in 274 cases) included an accelerator, a quaternary ammonium salt, on the mesh patch, whereas Mesh B (used in 145 cases) included a similar accelerator within the adhesive applicator. RESULTS: Wound complications (3.2 versus 7.6%; X2 = 3.86; df = 1; P = .049), early periprosthetic joint infections (0 versus 2.8%; X2 = 7.63; df = 1; P = .006), and 90-day reoperations for wound complications (0.4 versus 3.4%; X2 = 6.39; df = 1; P = .011) were significantly lower in patients who received Mesh A versus B, respectively. There was no difference in superficial surgical site infections (0.7 versus 0%; X2 = 1.06; df = 1; P = .302) or allergy rates (3.3 versus 4.1%; X2 = 0.12; df = 1; P = .655) between Mesh A and B. CONCLUSIONS: We observed significantly different performance in wound complications, early postoperative periprosthetic joint infections, and 90-day reoperation between the 2 designs. Having the accelerator in the applicator rather than on the mesh patch may lead to premature polymerization before bonding appropriately with the mesh to create the desired wound closure and seal. LEVEL OF EVIDENCE: Level III.

Does Lack of Initial Collar-Calcar Contact Influence Performance of Collared Cementless Femoral Stems?

Background: Initial stability of cementless stems is important to minimize the risk of subsidence, pain, and periprosthetic fracture after total hip arthroplasty (THA). Collared stems improve initial component stability when contacting the femoral calcar. Direct contact is not always achieved, and collared stem performance has not been studied in this context. We hypothesized that collared stems achieving direct contact would demonstrate reduced subsidence. Methods: A single-surgeon retrospective study of 482 consecutive primary THAs implanted between February 2020 and May 2023 using collared cementless stems was performed. The 2 cohorts included stems with initial collar-calcar contact vs stems without. Subsidence was evaluated by comparing intraoperative fluoroscopy to postoperative 8-week radiographs. Binary logistic regression identified independent risk factors for subsidence. Chi-square tests were used for categorical variables and t-tests for continuous variables. Results: Of stems, 63.9% achieved initial collar-calcar contact, while 36.1% did not. The rate (1.3% vs 19.0%; P < .001) and magnitude (0.02 mm, range 0-3 mm vs 0.35 mm, range 0-3 mm; P < .001) of subsidence were significantly higher among stems without initial contact. Stems without initial collar-calcar contact (P < .001) and male gender (P = .007) were independent risk factors for subsidence. Two patients with initial contact had nondisplaced calcar cracks and <3 mm of subsidence at 4 weeks, which healed with protected weight-bearing. Stem survivorship was 100% in both groups, with all achieving osteointegration and none needing revision. Conclusions: Excellent performance of collared cementless stems was observed at 8 weeks after primary THA. Initial collar-calcar contact lowered the risk and magnitude of minor subsidence but did not affect survivorship or fracture risk. Level of Evidence: Level III.

Scheduling and Vendor Consistency Improves Turnover Time Efficiency in Total Joint Arthroplasty.

BACKGROUND: Maximizing operative room (OR) efficiency is important for hospital efficiency, patient care, and positive surgeon and staff morale. Reducing turnover time (TOT) has become a popular focus to improve OR efficiency. The present study evaluated if TOT is influenced by changing case type, implant vendor, and/or laterality. METHODS: In total, 444 turnovers from January to July 2023 were retrospectively analyzed. All turnovers were same-surgeon turnovers between primary arthroplasty cases in dedicated, overlapping rooms. Single linear regression models tested the predictability of TOT based on case type, vendor, and laterality. A multivariate multiple regression and 1-way Analyses of Variance analyzed variables against each other. Independent sample t-tests evaluated TOTs when all variables were the same or different. RESULTS: Changing versus keeping the same case type increased TOT by 2.4 minutes (95% confidence interval [CI] = 0.7, 4.0; P = .004). Changing vendors increased TOT by 2.9 minutes (95% CI = 1.1, 4.7; P = .002). Laterality did not affect TOT, with a change of 0.9 minutes (95% CI = -0.6, 2.5; P = .229). Vendor (P = .030) independently predicted TOT when analyzed as a covariate with case type (P = .410). The TOT with same case type and vendor (mean 38.2 minutes; range, 22 to 62) was less than that of different case types and vendors (mean 41.4 minutes; range, 26 to 73) (P = .017). Mean TOT differed by 5.5 minutes when keeping all variables the same versus all different (P = .018). CONCLUSIONS: Maintaining a consistent case type, vendor, and laterality had a synergistic effect in reducing TOT in arthroplasty ORs with the same primary surgeon running 2 overlapping rooms. Changing vendor representatives was found to independently predict TOT increases, which is likely attributed to a disruption in workflow and collaboration of the multidisciplinary OR team. LEVEL OF EVIDENCE: Level III.