Posterior Cruciate Ligament Resection and Varus Correction in Total Knee Arthroplasty: A Study Using Computer-Assisted Surgery

Abstract

Background: Alignment correction is crucial for sustaining longevity and function in total knee arthroplasty (TKA). Although the posterior cruciate ligament (PCL) is a secondary stabilizer in the coronal plane, there have been few reports on the effects of PCL resection on varus correction. The study aim was to assess the effect of PCL resection performed using computer-assisted surgery (CAS) on varus correction in TKA.

Methods: From April 2019 through January 2021, patients with varus deformity of <20° and grossly intact PCLs were included. We used CAS to measure varus correction and gap change after PCL resection during CAS-TKA.

Results: Twenty-four female and eight male patients (40 operated knees) were included. The mean age was 68.7 ± 9.0 years, and the mean BMI was 26.5 ± 3.7 kg/m². The mean preoperative mechanical alignment was varus 5.7° ± 2.5°. We found that 1.4° ± 0.6° of varus correction occurred after PCL resection (P < .05). The mean extension and flexion medial-side gap increases were 0.4 mm and 2.0 mm, respectively (P < .05). The mean extension and flexion lateral-side gap increases were 0.4 mm and 1.6 mm, respectively (P < .05).

Conclusion: PCL resection during TKA resulted in a small degree of varus correction. The flexion gap was larger when the PCL was resected. These effects were predictable, so surgeons should be aware of these findings while performing TKA.

Keywords: Computer-assisted surgery; Gap balance; Posterior cruciate ligament release; Total knee arthroplasty; Varus correction.

Figure 1

Actual screen of varus alignment and full extension gap measurement.

Figure 2

Actual screen of flexion gap at 90° measurement.

Figure 3

Tensioning device.