Posterior condylar offset changes and its effect on clinical outcomes after posterior-substituting, fixed-bearing total knee arthroplasty: anterior versus posterior referencing

Abstract

Background: We sought to determine whether there was a difference in the posterior condylar offset (PCO), posterior condylar offset ratio (PCOR) and clinical outcomes following total knee arthroplasty (TKA) with anterior referencing (AR) or posterior referencing (PR) systems. We also assessed whether the PCO and PCOR changes, as well as patient factors were related to range of motion (ROM) in each referencing system. Methods: This retrospective study included 130 consecutive patients (184 knees) with osteoarthritis who underwent primary posterior cruciate ligament (PCL)-substituting fixed-bearing TKA. The difference between preoperative and postoperative PCO and PCOR values were calculated. Clinical outcomes including ROM and Western Ontario and McMaster University (WOMAC) scores were evaluated. Furthermore, multiple linear regression analysis was performed to determine the factors related to postoperative ROM in each referencing system. Results: The postoperative PCO was greater in the AR group (28.4 mm) than in the PR group (27.4 mm), whereas the PCO was more consistently preserved in the PR group. The mean postoperative ROM after TKA was greater in the AR group (129°) than in the PR group (122°), whereas improvement in WOMAC score did not differ between the two groups. Preoperative ROM was the only factor related to postoperative ROM in both groups. Conclusions: There was no difference in postoperative PCO in AR and PR group and the PCO was not associated with postoperative ROM. PCO was more consistently preserved after surgery in the PR group. The postoperative PCO and PCOR changes did not affect the postoperative ROM. Furthermore, similar clinical outcomes were achieved in the AR and PR groups. Trial registration: Retrospectively registered (Trial registration number: 06-2010-110).

Restoration of the Joint Line Configuration Reproduces Native Mid-Flexion Biomechanics after Total Knee Arthroplasty: A Matched-Pair Cadaveric Study

“…However, most knees in this study lacked advanced osteoarthritis necessitating TKA, so caution is required when extrapolating our findings to clinical practice. Third, this study featured PS prosthesis, which requires consideration of the implant feature prior to any broad generalizations, as implant design has been shown to be strongly correlated with knee kinematics [ 26 , 35 ]. Generally, when performing KA TKA, a cruciate-retaining (CR) prosthesis is recommended.…”

The Impact of a Gap Balancing or Measured Resection Surgical Technique on Posterior Condylar Offset and Patient-Reported Outcome Measures

“…As our cohort received PS TKAs, the weak correlations observed are unsurprising. It can be suggested that the inherent design features of the PS TKA prevent anterior translation of the femur during flexion delaying [8]. That study, however, examined 184 knees from 130 consecutive patients and primarily focused on differences between anterior-and posterior-referencing systems for measuring PCO.…”

“…There is controversy in the literature as to whether PCO impacts knee flexion after TKA [2,[4][5][6][7]. Some studies report correlation between the degree of offset and joint ROM, but others report discordance between the 2 measures [8]. Furthermore, randomized studies looking at the role of the posterior cruciate ligament in maximum postoperative flexion and functional outcome scores report no difference between posterior cruciate retaining (CR) and substituting implant designs [2,9].…”

Reliability of the posterior condylar offset

“…[2][3][4][5][6] In contrast, other authors state that the constitutional PCO's alteration had no significant clinical effect on the outcomes. [7][8][9][10][11][12][13] Different factors are the reason for these differences. 7 The comparison of pre-and postoperative PCO determined in "true lateral radiographs" presents several methodological errors.…”

“…Several studies reported that PCO restoration correlates with improved functional outcomes after primary TKA and revision 2–6 . In contrast, other authors state that the constitutional PCO's alteration had no significant clinical effect on the outcomes 7–13 . Different factors are the reason for these differences 7 .…”