Medial collateral ligament lengthening by standardized pie-crusting technique: A cadaver study

Abstract Introduction Pie-crusting (PC) is a tissue expansion technique using multiple perforation to lengthen the medial collateral ligament (MCL), but has still to be codified. Hypothesis Standardized MCL PC allows measured opening of the medial femorotibial (MFT) joint line, without risk of MCL tear. Material and method Thirty-one knees were dissected, with medial parapatellar arthrotomy and resection of the cruciate ligaments and menisci. The deep MCL bundle was sectioned, and the thick anterior bundle (AB) of the MCL was observed in each knee. Knees were randomly allocated between AB sparing (AB+; n = 15) or sectioning (AB−; n = 16). A graduated dynometric tensor applied constant 80 N distraction on the MFT joint line. MCL PC used a 19-G needle at the joint line, with a horizontal series of perforations every 2 mm over the width of the MCL. MFT compartment opening was measured after each PC series. Results Mean MFT space after sectioning the cruciate ligaments was 5.52 ± 0.37 mm, increasing by 1.64 ± 1.28 mm with AB sectioning. Twenty-five perforations were made in the AB+ and 16 in the AB− group. Final mean joint-line increase was 0.18 ± 0.18 mm in AB+ and 3.16 ± 2.70 mm in AB−. There were no MCL tears. Discussion MCL pie-crusting was reliable and reproducible, achieving progressive MFT joint-line lengthening to a mean 8.71 ± 2.62 mm when associated to sectioning of the cruciate ligaments and MCL AB. Type of study Cadaver. Level of evidence IV.