Comparison of patellar tracking according to different angles of external rotation of femoral component in varus knee of Asians

The prevalence of bilateral and ipsilateral radiographic osteoarthritis is high in White, Asian and Native Hawaiian/Pacific Islanders presenting for unilateral knee or hip arthroplasty

BACKGROUND

It is estimated that one-third of patients presenting with unilateral joint pain have contralateral osteoarthritis (OA) at first presentation. Most studies have primarily examined White patient cohorts. The purpose of this study was to determine the prevalence of contralateral joint OA for patients presenting for unilateral total knee (TKA), unicompartmental knee (UKA) or total hip arthroplasty (THA) among Asian, Native Hawaiian/Pacific Islander and White patients.

METHODS

Bilateral radiographic reports at initial presentation of 2,312 subjects who underwent unilateral arthroplasties (332 UKAs, 933 TKAs and 1,047 THAs) were reviewed. The presence of contralateral OA was recorded and compared by racial group and type of arthroplasty performed. Parametric statistical analyses were performed to determine differences between groups. Multivariable analyses were completed for each arthroplasty group to determine the influence on the presence of contralateral OA, presented as odds ratios and 95% confidence intervals.

RESULTS

Contralateral joint OA was present in 86.7%, 90.4% and 70.4% of UKA, TKA and THA patients, respectively. Concurrent hip OA was present in 41.6% and 59.5% of UKA and TKA patients. No racial differences in the prevalence of contralateral knee OA were found for knee arthroplasty patients. White patients (74.6%) had a greater prevalence of contralateral hip OA compared to Asians (66.5%, p = 0.037) amongst THA recipients. Increased age and body mass index were significantly associated with the presence of contralateral knee OA. Increased age, being male and being White were significant contributors for the presence of contralateral hip OA.

CONCLUSION

The prevalence of contralateral joint OA and concurrent hip OA is high in all three racial groups. Due to the extensive prevalence of contralateral and concurrent knee and hip OA, bilateral radiographic evaluation should be considered for all patients presenting with unilateral hip or knee pain due to OA.

Clinical Efficacy of Preoperative CT-Assisted Planning for Primary Total Knee Arthroplasty: A Pilot Randomized Clinical Trial

This study aims to determine the mean posterior condylar angle (PCA) in the included population and its relation to coronal alignment; and to know the clinical importance of the use of preoperative computed tomography (CT) scan in total knee arthroplasty (TKA). We randomized 50 patients with primary knee osteoarthritis into 2 groups. We used CT scan axial images to measure the PCA. In the first group we followed the CT scan plan (group 1), but in the second we did not follow the plan and adjusted rotation to the standard three degrees (group 2). The mean age of the included patients was 63 years. The radiological data of the included patients showed 5 patients with valgus deformity and 45 patients with varus deformity with the mean coronal alignment of 7.5 degrees. CT scan showed the mean PCA of 3.7 degrees (1.3 degrees). The axial knee postoperative X-ray showed the mean patellar tilt angle of 2.1 degrees (0.5 degrees) and 1.9 degrees (0.5 degrees) in groups 1 and 2, respectively. The congruence angle was 4 degrees (2.6 degrees) in group 1 and 5.5 degrees (3.2 degrees) in group 2. The median Knee Society functional score in group 1 was 85 (12), while it was 84 (7.5) in group 2. The median postoperative Western Ontario and McMaster Universities Arthritis Index score in group 1 was 84 (18.6) whereas 80.2 (13.6) in group 2. The median postoperative Bartlett score in group 1 was 30 (5), while it was 30 (6) in group 2. The use of preoperative CT scan did not improve the patient functional scores after TKA.

An optimization method for implantation parameters of individualized TKA tibial prosthesis based on finite element analysis and orthogonal experimental design

Background

Individualized and accurate implantation of a tibial prosthesis during total knee arthroplasty (TKA) can assist in uniformly distributing the load and reducing the polyethylene wear to obtain a long-term prosthetic survival rate, but individualized and accurate implantation of a tibial prosthesis during TKA remains challenging. The purpose of this study was to optimize and individualize the positioning parameters of a tibial prosthesis to improve its accurate implantation using a new method of finite element analysis in combination with orthogonal experimental design.

Methods

Ten finite element models of TKA knee joint were developed to optimize the implantation parameters (varus angle, posterior slope angle, and external rotation angle) of tibial prosthesis to reduce the peak value of the contact pressure on the polyethylene liner according to the method of finite element analysis in combination with orthogonal experimental design. The influence of implantation parameters on the peak value of the contact pressure on the polyethylene liner was evaluated based on a range analysis in orthogonal experimental design.

Results

The optimal implantation parameters for tibial prosthesis included 0° varus, 1° posterior slope, and 4° external rotation. Under these conditions, the peak value of the contact pressure on the polyethylene liner remained the smallest (16.37 MPa). Among the three parameters that affect the peak value of the contact pressure, the varus angle had the greatest effect (range = 6.70), followed by the posterior slope angle (range = 2.36), and the external rotation angle (range = 2.15).

Conclusions

The optimization method based on finite element analysis and orthogonal experimental design can guide the accurate implantation of the tibial prosthesis, reducing the peak value of the contact pressure on the polyethylene liner. This method provides new insights into the TKA preoperative plan and biomechanical decision-making for accurately implanting TKA prosthesis.