Postero-Central Slice Osteotomy of the Proximal Tibia: A Novel Technique for Correcting Resistant Tight Extension Gaps in Posterior-Stabilized Total Knee Arthroplasty for Varus Osteoarthritis

Background

The aim of total knee arthroplasty (TKA) is to circumvent the pain due to advanced osteoarthritis of the knee joint and correct the limb alignment and biomechanics to improve patients’ quality of life. Apart from medio-lateral balancing, balancing flexion and extension gaps is a prerogative to achieve good results. This study proposes a novel surgical technique of postero-central slice osteotomy of the proximal tibia (PCSO-PT) for correcting tight extension gaps in posterior-stabilized knees and assesses its clinical and functional outcomes.

Methods

A prospective study was conducted on 84 consecutive knees with tricompartmental osteoarthritis and varus deformity, requiring PCSO-PT during posterior-stabilized TKA between January 2016 and July 2018. Knee Society scores, flexion deformity, range of motion, antero-posterior instability, and complications were assessed at regular intervals for a minimum of 2 years postoperatively.

Results

Residual flexion deformities less than 11° after posterior capsular release were successfully corrected by the osteotomy. The mean preoperative flexion deformity of 18.1 ± 2.5° improved to 8.6 ± 2.2° intraoperatively after posterior capsular release from the femoral end and to 0.65 ± 0.76° intraoperatively immediately after the osteotomy, with no residual flexion deformity noted in any patient 6 weeks postoperatively. It had no negative effect on the significant post-TKA improvement of the mean Knee Society score from 32 ± 12 preoperatively to 94 ± 3 at the terminal follow-up. A direct correlation between preoperative flexion deformity and a resistant, tight extension gap (P = 0.003) was noted. There was no increase in coronal plane or sagittal plane instabilities in midflexion or on mobilization throughout the follow-up period, nor were any major adverse effects noted in this period.

Conclusions

A PCSO-PT is an effective and safe alternative to overcoming tight extension during TKA after femoral-end capsular release, instead of capsular release from the tibial end or midcapsular region.

Level of evidence

Level IV, therapeutic study.