The role of joint line position and restoration of posterior condylar offset in revision total knee arthroplasty : a systematic review of 422 revision knees arthroplasty

The aim of this systematic review was to evaluate the evidence on reservation of Posterior Femoral Condylar Offset (PFCO) and Joint Line (JL) after Revision Total Knee Arthroplasty (RTKA) for im- proved functional outcomes. A comprehensive search of PubMed, Medline, Cochrane, CINAHL, and Embase databases was conducted, with papers published from the inception of the database to October 2020 included. All relevant articles were retrieved, and their bibliographies were hand searched for further references on Posterior condylar offset and revision total knee arthroplasty. The search strategy yielded 28 articles. After duplicate titles were excluded, abstracts and full text were reviewed. Nine studies were assessed for eligibility, four studies were excluded because they did not fully comply with the inclusion criteria. Six articles were finally included in this systematic review. Based on this systematic review restoration of the JL and PFCO in RTKR is associated with a significant improvement in the post-operative range of motion, KSS, OKS, patellar function, and SF-36. Reservation of JL should be a major consideration when undertaking RTKA. Of note, increasing PFCO to balance the flexion gap while maintaining joint line should be well assessed intra-operatively. The upper limit of the PFCO that widely accepted is up to 40 % greater than that of the native knee. 4 mm is the upper limit for JL restoration. Level of evidence III.

Measurement of femoral posterior condylar offset and posterior tibial slope in normal knees based on 3D reconstruction

Background Femoral posterior condylar offset (PCO) and posterior tibial slope (PTS) are important for postoperative range of motion after total knee arthroplasty (TKA). However, normative data of PCO and PTS and the correlation between them among healthy populations remain to be elucidated. The purpose of this study was to determine PCO and PTS in normal knees, and to identify the correlation between them. Methods Eighty healthy volunteers were recruited. CT scans were performed followed by three-dimensional reconstruction. PCO and PTS were measured and analyzed, as well as the correlation between them. Results PTS averaged 6.78° and 6.11°, on the medial and lateral side respectively (P = 0.002). Medial PCO was greater than lateral (29.2 vs. 23.8 mm, P < 0.001). Both medial and lateral PCO of male were larger than female. On the contrary, male medial PTS was smaller than female, while there was no significant difference of lateral PTS between genders. There was an inverse correlation between medial PCO and PTS, but not lateral. Conclusions Significant differences exhibited between medial and lateral compartments, genders, and among individuals. An inverse correlation exists between PCO and PTS in the medial compartment. These results improve our understanding of the morphology and biomechanics of normal knees, and subsequently for optimising prosthetic design and surgical techniques.

The Influence of the Posterior Slope Angle and Posterior Condylar Offset in Posterior-Stabilized Total Knee Arthroplasty Was Analyzed From the Way of Constructing Flexion Gap

IntroductionThe purpose of this study was to compare the effects of two ways of establishing the flexion gap on the flexion angle and flexion-extension motion after posterior-stabilized （PS） prosthesis. A way for the posterior slope angle（PSA）and posterior condylar offset（PCO）were greater than preoperative, another for less than preoperative.Materials and MethodsThey are grouped according to the way flexion gaps are constructed. Data from 28 total knee arthroplasty（TKA）patients treated with propensity score match (PSM) were included. The difference of flexion angle and flexion-extension motion between the two groups was compared, and the influence of PCO and PSA on the flexion angle in the two ways was analyzed.ResultsPostoperative flexion degree of the two groups was 115.50±14.64° and 112.29±10.64° (P =0.553), and there was no statistical significance. Postoperative flexion-extension motion grade data of the decrease group was better than that of the increased group (P =0.031). Postoperative flexion angle was negatively correlated with PCO change in the increase group (r²=0.574 b '=-0.758 p=0.002).ConclusionsIncreasing the PSA and PCO to construct flexion gaps in PS TKA will cause problems with flexion-extension movements. It may be more reasonable to avoid excessive PSA and select appropriate PCO to reconstruct the flexion gap in PS prosthetic.

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

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.