Posterior condylar offset ratio more precisely reconstructed with robotic arm-assisted total knee arthroplasty when compared to conventional manual technique

Abstract

Aims and Objectives: The use of robotic-arm assisted total knee arthroplasty promises more precision in TKA implant technique. Precise implantation is elemental in improving functional and radiological outcome after TKA. The posterior condylar offset ratio (PCOR) is one important radiological parameter in total knee arthroplasty (TKA). The PCOR correlates with the maximum range-of-motion of the knee. A decrease of PCOR in TKA could lead to early impingement of the tibial insert with a consecutive decreased flexion range of the knee. The primary objective of this study was to determine differences in PCOR reconstruction after TKA between manual and robotic arm-assisted TKA surgery. Materials and Methods: A total of 80 patients undergoing primary TKA performed by one single senior surgeon were included in this prospective study. Two groups (Robotic arm-assisted TKA group, manual TKA group, n=40 patients each) were compared on the basis of hip-knee-ankle angle (HKA), medial proximal tibial angle (mPTA), distal lateral femoral angle (dLFA) and PCOR. Weight-bearing full-leg a.p. radiographs, as well as lateral knee radiographs, were performed pre- and postoperatively. All surgeries were performed with one single posterior stabilized TKA prosthesis type. Statistics consisted of parametric t-testing with a level of significance of p<0.05. Results: Preoperative limb alignment, mPTA and dLFA did not differ in between groups (each p>0.05). Postoperative mean PCOR was larger in the robotic arm-assisted TKA group (0.51 ± 0.05 vs. manual TKA group 0.47 ± 0.05, p=0.006). The absolute mean difference of pre- and postoperative PCOR was higher in the manual TKA group when compared to the robotic arm-assisted TKA group (-0.059 vs. -0.017, p=0.001). Manual TKA group showed a mean relative deviation of 12,03% (± 9,1%) in pre- to postoperative PCOR, whereas a mean relative deviation of 3.9 % (± 4.5%) was found in the robotic arm-assisted TKA group. Conclusion: Robotic arm-assisted TKA showed higher precision regarding postoperative PCOR with lower absolute mean differences and less relative deviation in pre- and postoperative PCOR when compared to manual TKA. A precise reconstruction of PCOR correlates with a better functional outcome as shown in previous studies before.

Robotic-arm assisted total knee arthroplasty is associated with improved accuracy and patient reported outcomes: a systematic review and meta-analysis

“…1 ) [ 12 , 24 , 35 , 42 ]. A list of the 16 studies which met the inclusion criteria are illustrated in Table 1 [ 4 , 18 – 20 , 23 , 25 , 28 , 30 – 32 , 36 , 44 , 49 – 52 ]. Nine studies were identified from Medline and PubMed, and seven additional studies from Google Scholar (Table 1 ).…”

“… ? Stryker Mako Smith et al [ 49 ] 2019 GS Prospective cohorts 120 RATKA vs 103 mTKA 68 vs 66 12 Triathlon PS (majority cementless, 10 in RATKA and 14 in mTKA cemented due to osteoporosis) Stryker Mako Sodhi et al [ 50 ] 2017 GS Retrospective cohorts 40 RATKA (early) vs 40 RATKA (late) vs 40 mTKA Not reported Not reported Not reported Stryker Mako Sultan et al [ 51 ] 2019 PM/ML Prospective cohorts 43 RATKA vs 39 mTKA 67 vs 66 1 – 1.5 Triathlon CR (cemented) Stryker Mako Tucking et al [ 52 ] 2019 GS Prospective cohorts 40 RATKA vs 40 mTKA ? ?…”

“…There were six clinical studies identified that reported on accuracy of component positioning and all compared RATKA against mTKA (Table 3 ) [ 4 , 20 , 44 , 50 – 52 ]. Three studies reported the posterior condylar offset ratio (PCOR) differences in RATKA and mTKA [ 20 , 51 , 52 ]. There was consistent evidence that RATKA resulted in significantly less differences between pre- and post-operative PCOR.…”

“…There was consistent evidence that RATKA resulted in significantly less differences between pre- and post-operative PCOR. Sultan et al and Tucking et al reported the lower differences between pre- and postoperative PCOR ( p = 0.01 and p = 0.001 respectively) [ 51 , 52 ]. When utilising RATKA, femoral components were placed with increased precision, within mean error range of 0.053 ± 0.020, as compared to 0.072 ± 0.035 when mTKA was utilised (Fig.…”

“…Femoral components mTKA 0.1 (± 1.6) varus vs RATKA 0.0 (± 1.4) varus, p = 0.506 Tibial components mTKA 1.9 (± 2.4) varus vs RATKA 0.9 (± 2.0) varus, p = 0.005 Femoral component external rotation relative to the transepicondylar axis mTKA 1.1 ± 2.3 vs RATKA 0.5 ± 2.3 degrees, (p = 0.195) Tibial slopes mTKA 3.7 ± 3.0 vs 3.2 ± 1.8 degrees, (p = 0.291) Naziri et al [36] 2019 Postoperative alignment was within + 3.0° of the mechanical axis for all patients in both RATKA and mTKA groups Savov et al [44] 2019 Limb alignment and restoration of the joint line mTKA no difference from RATKA RATKA deviation limb alignment to the intraoperative plan, mean = 2° (± 1.1) RATKA deviation of the medial proximal tibial (mPTA) and distal lateral femoral angle (dLFA) = 1° (± 0.9) for both Sultan et al [51] 2019 Postoperative PCOR, mean (SD) mTKA 0.53 (± 0.3) vs RATKA 0.49 (± 0.21), p = 0.024 Difference between pre-and postoperative PCOR, mean mTKA 0.03 vs RATKA 0.004, p = 0.01 Postoperative ISI outside of the normal range (0.8-0.12) mTKA 12 vs RATKA 4 Tucking et al [52] 2020 Postoperative PCOR, mean (SD) mTKA 0.47 (± 0.05) vs RATKA 0.51 (± 0.05), p = 0.006) PCOR (difference between pre-and postoperative), mean mTKA 0.059 vs RATKA -0.017, p = 0.001 Relative deviation of PCOR, mean (SD) mTKA 12.03% (± 9.1) vs RATKA 3.9% (± 4.5)…”