Preoperative flexion does not influence postoperative flexion after rotating-platform total knee arthroplasty

Mobile-bearing prosthesis and intraoperative gap balancing are not predictors of superior knee flexion: a prospective randomized study

PURPOSE

Range of motion is a crucial measure of the outcome of total knee arthroplasty. Gap balancing technique and mobile-bearing prosthesis can improve postoperative range of motion. The purpose of this study was to determine the factors that are predictive of the postoperative range of motion.

METHODS

A total of 94 knees with varus osteoarthritis were prospectively randomized to receive either a posterior-stabilized mobile-bearing or a posterior-stabilized fixed-bearing prosthesis. All preoperative and postoperative protocols and operative techniques were identical in the two groups. Extension and flexion joint gaps were measured using a tensor device during the operation. Multiple regression analysis was conducted to determine the best predictors of the knee flexion angle 2 years after the operation. The independent variables were type of prosthesis (mobile-bearing or fixed-bearing), difference between flexion and extension joint gaps (mm), age, gender, body mass index (BMI), preoperative and intraoperative knee flexion angles, change in posterior condylar offset, and posterior tilt of the tibial plateau.

RESULTS

The mean difference between flexion and extension joint gaps was 0.8 ± 1.3 (mean ± SD) mm for mobile-bearing and 0.8 ± 1.9 mm for fixed-bearing prosthesis. The mean flexion angle for mobile-bearing and fixed-bearing groups was 120 ± 16° and 116 ± 20° preoperatively (n.s.), 142 ± 9° and 141 ± 12° intraoperatively (n.s.), and 129 ± 10° and 128 ± 13° at 2 years postoperatively (p = 0.773), respectively. Predictors were identified in the following three categories: (1) preoperative flexion angle, (2) intraoperative radiographic flexion angle, and (3) BMI (R = 0.603, p < 0.001).

CONCLUSIONS

Mobile-bearing prosthesis and optimal gap balancing did not result in superior postoperative flexion angle. Better preoperative and intraoperative flexion angles and lower BMI were the significant predictors for better postoperative flexion angle.

LEVEL OF EVIDENCE

Therapeutic study, Level I.

Predictors of flexion using the rotating concave-convex total knee arthroplasty: preoperative range of motion is not the only determinant

PURPOSE

The range of motion achieved after a total knee arthroplasty (TKA) affects many daily activities and overall patients' satisfaction. This study aims to define the determinants affecting post-operative midterm active flexion according to a specific cruciate-sacrificing prosthesis, the rotating concave-convex (ROCC(®)) TKA.

METHOD

Four hundred and eighty-four consecutive patients (584 TKAs) were prospectively followed. After baseline patient demographics and anatomical characteristics, clinical and radiological post-operative assessments were periodically recorded. The rotational alignment of the femoral component was additionally reported for 120 patients. Eligibility for final inclusion was a minimum of 5-year follow-up. Univariate analyses followed by a multivariate model were fitted to determine the independent predictors of midterm active knee flexion.

RESULTS

Thirty-four TKA (5.8%) were excluded for a secondary surgery before their 50 years, 69 patients died (11.8%), and 21 (3.6%) were lost to follow-up. Overall, 460 TKAs were included. The post-operative mean knee flexion angle was measured at 127.7° ± 9.3°. Significant factors affecting final flexion under univariate analyses were the patient height and body mass index, the absence of previous surgery, a depressive state, the preoperative flexion angle, a preoperative flexion contracture, a patellar residual subluxation, the reconstructed patellar height, and the rotation of the femoral component. The multivariate model confirmed the patient's height, a depression, the preoperative flexion angle, a patellar residual subluxation, and the patellar height as statistically significant determinants.

CONCLUSION

Aside from the preoperative flexion angle, numerous predictors of flexion, both patient- and procedure-related were identified. Surgeons should take these into account both when adequately informing their patient before surgery and when performing the arthroplasty itself.

LEVEL OF EVIDENCE

Prognostic, Level II.

Do various factors affect the frequency of manipulation under anesthesia after primary total knee arthroplasty?

BACKGROUND

One of the most important goals of primary total knee arthroplasty (TKA) is to achieve a functional range of motion (ROM). However, up to 20% of patients fail to do so, which can impair activities of daily living.

QUESTIONS/PURPOSES

The purpose of this study was to evaluate the effect of various (1) demographic factors; (2) comorbidities; and (3) knee-specific factors on the frequency of manipulation under anesthesia, which was used as an indicator of knee stiffness after a primary TKA.

METHODS

We evaluated the registries of two high-volume centers and reviewed all 3182 TKAs that were performed between 2005 and 2011 to identify all patients who had undergone manipulation under anesthesia (MUA). A total of 156 knees in 133 patients underwent MUA after an index arthroplasty. These patients were compared in a one-to-four ratio with a group of patients with satisfactory ROM drawn from the same database who met prespecified criteria and who had not undergone MUA. Effects of various factors, including age, sex, body mass index, race, comorbidities, and the underlying cause of knee arthritis, were compared between these two cohorts using multivariable logistic regressions.

RESULTS

After controlling for various confounding, nonwhite race was associated with an increase (odds ratio [OR], 2.01; p=0.03), and age≥65 years (OR, 0.17; 95% confidence interval [CI], 0.04-0.74; p=0.0179) was associated with a reduction in the incidence of MUA. In comorbidities, diabetes (OR, 1.72; 95% CI, 1.02-2.32; p=0.03), high cholesterol levels (OR, 2.70; p=0.03), and tobacco smoking (OR, 1.59; 95% CI, 1.03-2.47; p=0.03) were associated with an increase in frequency of MUA. In knee-specific factors, preoperative knee ROM of less than 100° (OR, 0.80; p<0.0001) and knee osteonecrosis (p=3.61; 95% CI, 1.29-10.1; p=0.014) were associated with increased frequency of MUA.

CONCLUSIONS

We identified several demographic, medical, and knee-specific factors that were associated with poor postoperative ROM in our patients undergoing TKA. Patients who have multiple risk factors may benefit from preoperative counseling to set realistic ROM expectations.

LEVEL OF EVIDENCE

Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Total knee arthroplasty in Asian subjects: preoperative range of motion determines postoperative range of motion?

OBJECTIVE

To evaluate whether preoperative range of motion is a key determinant of postoperative range of motion in Asian patients undergoing conventional total knee arthroplasty.

METHODS

A retrospective review of 302 patients who underwent primary total knee arthroplasty performed by a single surgeon was conducted. Patients who had a fixed flexion deformity of ≥15° were excluded. Postoperative range of motion (ROM) was measured prospectively. Patients were stratified into two groups: preoperative ROM < 110° and preoperative ROM ≥ 110°. Postoperative ROM and mean change in ROM at 6 months and 2 years of follow-up were then compared using Student's t-test.

RESULTS

Group of ROM < 110° had a poorer postoperative range of motion at both 6-months and 2-years of follow-up than Group of ROM ≥ 110° (P < 0.001). Postoperatively, Group of ROM < 110° had gained range of motion whereas Group of ROM ≥ 110° had lost range of motion (P < 0.001).

CONCLUSIONS

Similar to the Western population, preoperative range of motion is a key determinant of postoperative range of motion in Asian patients. This should be taken into consideration by surgeons during preoperative planning and in managing patients' expectations.