Mid-Flexion, Anteroposterior Stability of Total Knee Replacement Implanted with Kinematic Alignment

Abstract

UpdateThis article was updated on January 4, 2023, because of a previous error, which was discovered after the preliminary version of the article was posted online. On page 16, in Figure 5, the x-axis that had read “P<0.0086” now reads “KSS Pain (p=0.02),” and the value for the MS group that had read “48.9” now reads “48.8.”This article was updated on January 6, 2022, because of a previous error. On page 13, in the section entitled “Results,” the sentence that had read “However, when only the subset of female subjects was considered, the MS group demonstrated significantly less anteroposterior laxity in 90° of flexion than the MS group (2.3 versus 5.4 mm; p = 0.008).” now reads “However, when only the subset of female subjects was considered, the MS group demonstrated significantly less anteroposterior laxity in 90° of flexion than the PS group (2.3 versus 5.4 mm; p = 0.008).”Background:Stability in mid-flexion is important for satisfactory clinical outcomes following total knee arthroplasty (TKA). The purpose of the present study was to compare the anteroposterior stability of knees that had been treated with a posterior-stabilized (PS) device or a medial-stabilized (MS) device. We hypothesized that mid-flexion laxity would be greater in the PS group and that clinical outcome scores would be better for the group with lower laxity.Methods:Sixty-three patients who had been randomly selected from a larger randomized, prospective, blinded clinical trial underwent primary TKA with either a PS implant (n = 30) or an MS implant (n = 33). Range of motion, the Knee Society Score (KSS), and the Forgotten Joint Score (FJS) were collected, and anteroposterior laxity with the knee in 45° and 90° of flexion was evaluated with stress radiographs.Results:In 45° of flexion, the MS group demonstrated significantly less total anteroposterior displacement than the PS group (mean, 3.6 versus 16.5 mm; p ≤ 0.0001). In 90° of flexion, the total anteroposterior displacement was not significantly different for the 2 groups when both male and female patients were included (mean, 3.9 versus 5.9; p = 0.07). However, when only the subset of female subjects was considered, the MS group demonstrated significantly less anteroposterior laxity in 90° of flexion than the PS group (2.3 versus 5.4 mm; p = 0.008). The groups did not differ significantly in terms of preoperative age, body mass index, sex distribution, FJS, KSS, or range of motion, and they also did not differ in terms of postoperative FJS or range of motion. However, all 33 patients in the MS group returned to sports as indicated in question 12 of the FJS, compared with 19 subjects in the PS group (p = 0.0001). The postoperative KSS Pain, Pain/Motion, and Function scores were all significantly higher in the MS group than the PS; specifically, the mean KSS Pain score was 48.8 in the MS group, compared with 44.8 in the PS group (p = 0.02); the mean KSS Pain/Motion score was 98.4 in the MS group, compared with 89.5 in the PS group (p < 0.0001); and the mean KSS Function score was 95.5 in ...

The Early Clinical Outcomes Following Unrestricted Caliper Verified Kinematic Alignment Using a Medial Stabilized Design Total Knee Arthroplasty With a Cruciate Retaining Insert

“…The difference in the FJS at 6 months and 12 months did not meet the MCID of 16.6 established by Clement et al., with a difference of 14.1; however, it is worth noting that the difference was calculated by using the 6-month scores as the baseline rather than the preoperative timepoint used for the MCID calculation [ 50 ]. The overall FJS of 60.7 at 1 year is comparable to the FJS of other kinematically aligned MS implants reported in literature that ranges from 56.9 to 79.3 [ 1 , 45 , 51 , 52 ]. Similarly, in the study by Risitano et al.…”

Knee

“…The resultant cohorts were relatively small, with 30 PS and 33 MS knees included in a study from Spokane (Washington, USA) . 7 The MS bearing provided decreased anterior-posterior laxity in mid-flexion compared to PS bearings for males and females, with a similar finding in 90° of flexion for females that was not appreciated in males. Preoperative and postoperative knee range of motion was similar between the two groups, with no difference in postoperative Forgotten Joint Scores.…”

The Joint Awareness Score: A Shortened, Simplified, Improved Alternative to the Forgotten Joint Score

“…Additionally, it is possible that the surgical technique (kinematic alignment) and the TKA device utilized (medial-stabilized) may produce scores that are not directly comparable to other alignment techniques and implant designs. However, improved outcomes have been reported for this device [ 19 , [39] , [40] , [41] , [42] , [43] , [44] , [45] ] and procedure [ [46] , [47] , [48] , [49] , [50] , [51] ], therefore this could prove to be a worst-case scenario, likely to produce a substantial percentage of scores at the ceiling, yet this problem was not encountered.…”