The posterior condylar offset ratio and femoral anatomy in anterior versus posterior referencing total knee arthroplasty

Kang

et al. 2020

Knee Surg & Relat Res

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).

Section: Discussionmentioning

confidence: 81%

“…On the other hand, preservation of the posterior condylar offset (PCO) and posterior condylar offset ratio (PCOR) was reported to be related to the degree of maximal flexion after TKA [7][8][9][10][11][12][13][14][15][16]. The PCO or PCOR after TKA could differ based on the referencing system used.…”

Section: Introductionmentioning

confidence: 99%

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

Kang

et al. 2020

Knee Surg & Relat Res

J Orthop Surg (Hong Kong)

“…With respect to posterior clearance, PCO and PCO ratio (PCOR) are important outcome measures of knee joint function 3,10,11 and these values have been reported to increase postoperatively. 12,13 Almeida et al 13 reported that postoperative PCOR did not differ between the AR and PR methods, showing a significant increase in both cases. For PCO, opinions are divided as to whether it influences ROM 3,6,7,11,14 or not.…”

Section: Discussionmentioning

confidence: 95%

Which is better? Anterior or posterior referencing for femoral component position in total knee arthroplasty

Nojiri

Hayakawa

Date

et al. 2021

When sizing the femoral component or determining its placement in total knee arthroplasty (TKA), if the anterior–posterior diameter of the femoral condyle is between component sizes, the selected size will differ depending on whether anterior referencing (AR) or posterior referencing (PR) is used. As a result, the amount of resected bone will also vary. In the present prospective study, we compared the two referencing methods to determine which is more suitable for individual patients. We recruited 58 patients (92 joints) who received TKA using the standard technique with intermediate-size components. AR was used in 26 joints, and PR in 23 joints. Seventeen of the patients underwent same-day bilateral TKA in which components of different sizes were used for the left and right joints. AR resulted in significantly smaller anterior and posterior offsets than PR. Preoperative clinical evaluation revealed no significant differences among cases in which intermediate-size components were indicated, or those in which components of different sizes were indicated. When an intermediate-sized component was indicated using the AR method, moving the sizer forward resulted in a larger posterior gap, but this technique was nevertheless considered acceptable. AR is likely to be more suitable than PR as it achieves more physiological anterior clearance.

“…Lateral radiographic images of the knee were analyzed on our picture archiving and communication system (PACS, SECTRA Inc., Shelton, CT, USA) and measured for posterior condylar offset (PCO), posterior condylar offset ratio (PCOR), and tibial slope as described by Mont, Almeida, and Bernhardson, respectively. [12][13][14] Soft-tissue envelope thickness in the prepatellar and pretubercle region was calculated by the methods used by Watts and colleagues. 15 The AP radiograph was then evaluated for joint line elevation using the femoral epicondylar landmarks, as outlined by Servien et al 16 One author (C.M.H.)…”

Section: Methodsmentioning

confidence: 99%

Radiographic Findings in Flexion Instability after Total Knee Arthroplasty

et al. 2021

Flexion instability (FI) is one of the leading causes of knee pain and revision surgery. Generally, the biomechanical etiology is considered to be a larger flexion than extension gap. This may be due to mismatch of components sizes to the bone or malalignment. Other factors such as muscle weakness may also play a role, and the diagnosis of FI after total knee arthroplasty (TKA) relies on a combination of patient's complaints during stair descent or walking and physical examination findings. Our study examines the role of implant positioning and sizes in the diagnosis of FI. A retrospective review of 20 subjects without perceived FI and 13 patients diagnosed with FI after TKA was conducted. Knee injury and osteoarthritis outcome scores (KOOS) were documented, and postoperative radiographs were examined. Measurements including included tibial slope, condylar offset, femoral joint line elevation along with surrogate soft-tissue measures for girth and were compared between groups. The FI group was found to have a significantly lower KOOS score compared with the non-FI group (55.6 vs. 73.5; p = 0.009) as well as smaller soft-tissue measurements over the pretubercle region (6.0 mm vs. 10.6 mm; p = 0.007). Tibial slope, condylar offset ratios, and femoral joint line elevation were not significantly different between the FI and non-FI groups. We noted a significant difference in tibial slope in posterior-stabilized implants in subjects with and without FI (6.4° vs. 1.5°; p = 0.003). Radiographic measurements consistent with malalignment were not indicative of FI. X-ray measurements alone are not sufficient to conclude FI as patient symptoms, and clinical examinations remain the key indicators for diagnosis. Radiographic findings may aid in surgeon determination of an underlying cause for an already identified FI situation and help in planning revision surgery.