Do Survival and Clinical Outcomes of Isolated Polyethylene Insert Exchange for TKA Instability Differ with Hyperextension?

Overall IPIE survival was 83% at 5 years and 57% at 10 years. Survival did not differ significantly according to the presence of hyperextension.

Participants and Methods

46 patients: 18 without and 28 with >5° hyperextension; mean age 70.1 years, 91% women, mean follow-up 44.8 months. This retrospective comparison selected patients with satisfactory implant fixation/alignment and achievable intraoperative balance. Failure was analyzed with Kaplan–Meier and Cox regression.

The order in which you read the painting.

Clinical scores before and after TKA and insert exchange are compared in groups with and without hyperextension. The number included in each analysis differs by time point. Insert exchange was performed in selected patients after checking component position/fixation and ligaments. Although 46 patients were enrolled, some Figure 2 comparisons used fewer. Discuss long-term failure alongside 83% survival at 5 years and 57% at 10 years. A nonsignificant group difference does not prove equivalence in every setting.

Main Findings

IPIE survival was 83% at 5 years and 57% at 10 years, without a significant difference by hyperextension. Mean insert thickness increased from 11.9 ± 1.8 to 17.1 ± 3.1 mm. The hyperextension group used thicker inserts, but ROM and clinical scores did not differ significantly.

The point of reading on surgery

These findings support considering limited revision in TKA with satisfactory fixation and alignment. Both the 5-year outcomes and the possibility of failure at 10 years should be discussed; the approach does not apply to every instability pattern.

Limitations

This retrospective study included 46 selected cases, without direct comparison with full revision. The 10-year estimate extends beyond the mean follow-up and requires cautious interpretation. The publication year is 2024.

Let's put it briefly.

What did this study confirm?

Overall IPIE survival was 83% at 5 years and 57% at 10 years. Survival did not differ significantly according to the presence of hyperextension.

Can it be applied directly to individual patients' treatment decisions?

This was a retrospective study of 46 selected cases, without direct comparison with full revision. The 10-year estimate extends beyond the mean follow-up and requires cautious interpretation.

Keywords

Hyperextension
Isolated polyethylene insert exchange
Joint instability
Polyethylene
Reoperation
Arthroplasty, Replacement, Knee
Joint Instability
Range of Motion, Articular

Abstract · Original text

Byung Sun Choi, Du Hyun Ro, Myung Chul Lee, Hyuk-Soo Han. Isolated Polyethylene Insert Exchange for Instability after Total Knee Arthroplasty: Comparable Survival Rates and Range of Motion and Improved Clinical Scores Regardless of Hyperextension. Clinics in orthopedic surgery. 2024;16(4):550-558. doi:10.4055/cios23163.

BACKGROUND

Isolated polyethylene insert exchange (IPIE) has not been established as a treatment option for hyperextension instability after primary total knee arthroplasty (TKA). The purpose of the study was to evaluate the survival rate and clinical outcomes of IPIE for the treatment of instability with or without hyperextension after TKA.

METHODS

This study retrospectively reviewed 46 patients who underwent IPIE for symptomatic prosthetic knee instability by dividing them into 2 groups based on the presence of hyperextension (without for group I and with for group IH). Patient demographics, clinical scores, radiographic data, range of motion (ROM), and surgical information were collected. Clinical failure was defined as a subsequent surgery following IPIE for any reason. The survival rate of IPIE and differences in demographics, clinical scores, and ROM were compared.

RESULTS

There were 46 patients (91% were women) with an average age of 70.1 years and a mean follow-up of 44.8 months. The average time between primary TKA and IPIE surgery was 6.5 ± 4.2 years, and during IPIE, 2 out of the 8 cruciate-retaining inserts were converted to "deep-dish" ultracongruent inserts while the insert thickness increased from 11.9 ± 1.8 mm to 17.1 ± 3.1 mm. After IPIE surgery, a significantly thicker tibial insert was used in the group with hyperextension (15.39 ± 2.4 mm for group I, 18.3 ± 2.9 mm for group IH; p < 0.001 by independent t-test), and no significant differences were observed in the ROM and clinical scores before and after IPIE between the 2 groups. The overall survival rate for IPIE was 83% at 5 years and 57% at 10 years, and there were no statistically significant differences between the groups using the Cox proportional hazards regression model.

CONCLUSIONS

IPIE demonstrated an overall survival rate of 83% at 5 years with no difference in the recurrence of instability regardless of hyperextension. This study highlighted the effectiveness of using thicker inserts to resolve instability without significant differences in the ROM or clinical scores between the groups, suggesting its potential as a decision-making reference for surgeons.

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The original paper.

Isolated Polyethylene Insert Exchange for Instability after Total Knee Arthroplasty: Comparable Survival Rates and Range of Motion and Improved Clinical Scores Regardless of Hyperextension

Byung Sun Choi, Du Hyun Ro, Myung Chul Lee, Hyuk-Soo Han
Clinics in Orthopedic Surgery · 2024

DOI · 10.4055/cios23163 PubMed Based data

The first one examined.