Serial valgus stability and clinical outcomes after percutaneous medial collateral ligament release during transtibial medial meniscus posterior root repair

Medial meniscus posterior root tears (MMPRTs) abolish hoop tension and mimic total meniscectomy. During transtibial pullout repair, percutaneous release (“pie-crusting”) of the superficial medial collateral ligament (sMCL) widens the medial compartment, but the course of postoperative medial laxity and its relation to osteoarthritis (OA) progression have not been quantified. Of 53 screened patients, 47 formed the study cohort; 46 with evaluable 12-month radiographs comprised the primary analysis, and one who underwent conversion to total knee arthroplasty after repair failure was retained as a treatment failure. All patients underwent arthroscopic transtibial MMPRT repair with percutaneous sMCL release and brace-free rehabilitation. Lysholm score, visual analogue scale (VAS) pain, and medial clear space (MCS) on valgus stress radiographs were assessed preoperatively and at 3, 6, and 12 months using linear mixed-effects models. Factors associated with 12-month radiographic OA progression were examined by exploratory Firth logistic regression. Lysholm score improved from 23.3 ± 10.3 to 96.0 ± 5.4 and VAS pain decreased from 4.4 ± 1.3 to 0.7 ± 0.7 at 12 months (both Holm-adjusted p < 0.001). MCS increased from 0.45 ± 0.14 cm preoperatively to the greatest observed value of 0.65 ± 0.12 cm at 3 months and decreased to 0.57 ± 0.10 cm at 12 months, remaining greater than baseline (adjusted p < 0.001). Seventeen of 46 patients (37.0%) showed radiographic OA progression. In exploratory multivariable analysis, Kellgren–Lawrence (KL) grade 2 (adjusted odds ratio [aOR] 22.63; 95% CI 1.03–4812.28; p = 0.047), preoperative subchondral insufficiency fracture of the knee (SIFK; aOR 11.71; 95% CI 1.19–424.20; p = 0.034), and a more medial postoperative weight-bearing line (WBL) ratio (aOR 0.78 per 1% increase; 95% CI 0.59–0.89; p < 0.001) were associated with progression. Final MCS did not differ between groups (0.57 ± 0.12 vs. 0.58 ± 0.10 cm; p = 0.938). Percutaneous sMCL release during transtibial MMPRT repair was associated with increased medial opening that was greatest at 3 months and decreased through 12 months while remaining above baseline. In the absence of a non-release or braced control group, these data neither establish the comparative safety of sMCL release nor demonstrate that postoperative bracing is unnecessary, and an effect of the release on OA progression cannot be excluded.