A horizontal cleavage tear is a degenerative tear of a meniscus, extending into the meniscus substance, and cleaving it horizontally into two parts, like a clam.
The horizontal tear is a shearing injury. It is revealed by probing of the meniscus.
A meniscal cyst may form in the joint line if fluid is forced through the cleavage by a valve-like action.
Probing a trimmed horizontal cleavage tear during an arthroscopy
Horizontal cleavage tears and meniscal cysts
The clam-like nature of such a meniscus tear may allow fluid to be forced out into the tissues on the side of the joint, forming a meniscal cysts - a tender palpable fluid-filled lump in the joint line.
Management of horizontal cleavage tears
These tears are difficult to manage. Surgeons will often choose a partial meniscectomy or even a total meniscectomy, preserving what they can of the rim. Repair might be attempted after roughening up the inside of the tear, pushing a lump of blood clot (from the patient) into the defect, and suturing it in place.
Repair of isolated horizontal meniscal tears with all-inside suture materials using the overlock method: outcome study with a minimum 2-year follow-up. Tiftikçi U and Serbest S. J Orthop Surg Res. 2016; 11: 131.
Horizontal Cleavage Meniscus Tear Treated With All-inside Circumferential Compression Stitches. Woodmass JM, Johnson JD, Wu IT, Saris DBF, Stuart MJ and Krych AJ. Arthrosc Tech. 2017 Aug; 6(4): e1329–e1333.
Surgical management of degenerative meniscus lesions: the 2016 ESSKA meniscus consensus. Beaufils P, Becker R, Kopf S, Englund M, Verdonk R, Ollivier M and Seil R. Knee Surg Sports Traumatol Arthrosc. 2017; 25(2): 335–346.
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Video courtesy of Dr Ram Venkatesh