One-Year Functional Outcomes of Medial Congruent, Manually Instrumented Total Knee Replacements

TL;DR

This study shows that a specific type of knee replacement surgery improves patient outcomes and maintains results over one year.

Contribution

The study demonstrates the effectiveness of manually instrumented, mechanically aligned TKA with a medial congruent design.

Findings

KOOS-JR scores improved from 56.2 preoperatively to 89.4 at one year.

No revision surgeries were needed, resulting in 100% implant survivorship.

Only 3% of patients required manipulation under anesthesia for stiffness.

Abstract

Aim: The primary objective of this study was to evaluate improvement in Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) following mechanically aligned, manually instrumented total knee arthroplasty (TKA) using a medial congruent design. Secondary objectives included assessment of complication rates, reoperations, and revision-free survivorship at one year.

Methods: A retrospective chart review was conducted of 200 consecutive primary TKAs performed by a single surgeon. The cohort included 90 male and 110 female patients with a mean age of 73 years at the time of surgery. All procedures were performed using manual instrumentation with mechanical alignment targets and a medial congruent polyethylene design. Patient-reported outcomes were assessed using the KOOS-JR preoperatively, at six weeks postoperatively, and at approximately one year following surgery. Complications, reoperations, and revision procedures were recorded. Descriptive statistics were used to summarize outcomes and complication rates.

Results: The mean preoperative KOOS-JR score was 56.2. At six weeks postoperatively, the mean KOOS-JR score improved to 78.3, demonstrating substantial early functional improvement. At an average follow-up of one year, the mean KOOS-JR score further improved to 89.4, indicating sustained and clinically meaningful gains in pain relief and function. No revision surgeries were required during the study period, resulting in 100% implant survivorship at the latest follow-up. Six patients (3%) required manipulation under anesthesia for postoperative stiffness. No cases of early aseptic loosening, mechanical failure, or implant-related instability were identified.

Conclusions: In this retrospective series, mechanically aligned primary TKA performed with manual instrumentation and a medial congruent implant design resulted in significant improvements in patient-reported outcomes, low complication rates, and excellent early implant survivorship. The observed improvements in KOOS-JR scores exceeded established thresholds for clinical significance and were maintained at one year postoperatively. These findings support the effectiveness and reproducibility of this surgical approach for primary TKA and suggest that favorable outcomes can be achieved without the routine use of advanced alignment technologies. Longer-term follow-up and comparative studies are warranted to confirm durability and assess outcomes relative to alternative alignment strategies.

Figures