Comparison of Postoperative Effects between Medial Pivot Prosthesis and Posterior Stabilized Prosthesis

Abstract

Objective: To compare the postoperative inflammation and pain response between medial pivot (MP) and posterior stabilized (PS) prostheses among total knee arthroplasty (TKA) patients.

Methods: A prospective cohort study was conducted from January 2019 to May 2019 at the Affiliated Hospital of Qingdao University. The study included patients diagnosed with stage III or IV Kellgren-Lawrence knee osteoarthritis (KOA) who had failed conservative treatment, had undergone no previous knee surgeries, had varus substantial deformities (11°-20° deviation), and had received their first unilateral TKA. A total of 109 patients who underwent PS prosthesis TKA and 98 patients who underwent MP prosthesis TKA were continuously enrolled. Inflammation biomarkers, such as leukocyte (white blood cells), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), together with hemoglobin (Hb), the visual analog pain score (VAS) and range of motion (ROM) were compared between the two groups. The Student t-test was applied to analyze continuous parameters, and the χ² -test was used for categorical parameters. The linear mixed model was used for the repeated measurement data from the follow-up visits. Multivariate backward logistic and linear regression models were used to determine the factors potentially influencing prostheses and VAS scores.

Results: All these enrolled patients were followed up at 2, 4, 7, and 30 days after TKA. There were no significant differences between the PS group and the MP group in body mass index (BMI), gender, laterality, usage of nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids, and drain tube extubation time (P > 0.05). Compared with the PS group, the MP group were older (67.5 years vs 65.4 years), and had a higher mid-vastus approach rate (67.3% vs 26.6%), a shorter tourniquet duration (68.3 ± 10.2 h vs 73.9 ± 11.2 h), a larger prosthetic pad (10.8 ± 1.2 mm vs 10.4 ± 1.2 mm), and a lower drain tube diversion volume (187.6 ± 119.3 mL vs 234.0 ± 155.7 mL). In the linear mixed model, MP prostheses had less CRP and ESR elevation and less Hb decrease than PS prostheses (P for group × time < 0.001). There were no significant differences in the changing trends between MP and PS prostheses by time for VAS scores and ROM. In the multivariate logistic regression model, MP prostheses showed significant differences compared with PS prostheses in treatment approach (odds ratio [OR] = 3.371, 95% confidence interval [CI]: 1.953-7.127; P < 0.001), ultrasound treatment start time (OR = 2.669, 95% CI: 1.385-5.141; P = 0.003), and tourniquet duration (OR = 0.954, 95% CI: 0.925-0.984; P = 0.003). Higher VAS scores on the second day postoperatively were related to high VAS scores preoperatively, use of opioids, high drain tube diversion, long tourniquet duration, and long drain tube extubation (P < 0.05), respectively.

Conclusion: The MP prostheses showed potential advantages compared with PS prostheses in TKA in inflammatory responses.

Keywords: Inflammation; Medial pivot prostheses; Posterior stabilized prostheses; Postoperative effects; Total knee arthroplasty.

Fig. 1

The flow chart shows the patient enrollment process.

Fig. 2

A case of a 67‐year woman who underwent posterior stabilized total knee arthroplasty. (A) Anteroposterior X‐ray of knee demonstrated right knee osteoarthritis of Kellgren–Lawrence stage IV. (B) A posterior stabilized (PS) box cutting jig was placed after femoral cut, (C) Image of bone after box cutting. (D) The whole package of prosthesis and polyethylene with a cam was properly placed. (E) Postoperative anteroposterior X‐ray of the knee.

Fig. 3

A 65‐year woman who underwent medial pivot total knee arthroplasty. (A) Preoperative anteroposterior X‐ray of the knee demonstrated right knee osteoarthritis of Kellgren–Lawrence stage IV. (B) Due to a different design of prosthesis less box cutting was done to compare the posterior stabilized total knee arthroplasty and more bone was preserved. (C) Polyethylene without a cam was placed after cementing of the femoral and tibial components. (D) Postoperative anteroposterior X‐ray of the patient.

Fig. 4

The graphs show the changes of means and standard deviations (SD) in leukocyte (white blood cells) levels (A), erythrocyte sedimentation rate (ESR) (B), C‐reactive protein (CRP) levels (C), and hemoglobin (Hb) levels (D) after total knee arthroplasty (TKA) in medial pivot (MP) and posterior stabilized (PS) groups.

Fig. 5

The graphs show the changes of means and standard deviations (SD) in visual analog pain score (VAS) (A) and range of motion (ROM) (B and C) after total knee arthroplasty (TKA) among medial pivot (MP) and posterior stabilized (PS) groups.