High-grade MCL pie-crusting during root repair did not leave clinical valgus laxity

Design

Retrospective case series, level IV

Population

21 patients after medial meniscus posterior root repair with high-grade MCL pie-crusting

Primary outcome

Side-to-side medial gapping on valgus stress radiographs

Effect

1.21 mm (95% CI 0.73 to 1.70), below 3.2 mm threshold (p < 0.001)

Percutaneous pie-crusting of the medial collateral ligament opens a tight medial compartment for meniscal surgery. Some surgeons release well beyond routine perforation, and whether that leaves the knee lax has been unclear.

A retrospective case series reviewed 21 patients who had medial meniscus posterior root repair with high-grade pie-crusting, defined as an audible, palpable release with at least 6 mm of medial opening. At about six months, valgus stress radiographs at 20° showed medial gapping of 7.84 mm in the operated knee against 6.62 mm on the other side, a mean difference of 1.21 mm (95% CI 0.73 to 1.70). That is well below the 3.2 mm threshold associated with clinically meaningful laxity.

This is reassuring for surgeons who need generous access to the posterior horn, but it rests on 21 knees, radiographic gapping rather than symptoms, and six months of follow-up.

• High-grade MCL pie-crusting increased medial gapping by about 1 mm on stress radiographs at six months.
• That increase stayed below the 3.2 mm threshold linked to clinical valgus instability.
• Consider stress radiographs at follow-up if a patient reports medial instability after extensive release.
• Long-term effects on the MCL and on meniscal repair healing were not assessed.

Why it matters

Surgeons hesitant to release enough for safe posterior root access have some reassurance that the ligament tolerates it.

Don't overread it

A 21-patient case series with radiographic outcomes at six months cannot establish long-term safety.

The statistics, in plain English

The upper end of the confidence interval, 1.70 mm, is still about half the 3.2 mm instability threshold, so even the worst plausible average is below it.

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