What did the study look at?
The ligament on the inner side of the knee (medial collateral ligament, MCL) can be tight in some patients. This can make it harder to see and safely work on the back of the inner meniscus during arthroscopy, and it can affect soft-tissue balance in knee replacement and in bone realignment surgery around the knee. Pie-crusting (PC) means gradually loosening this ligament by making many small punctures through the skin with a needle.
The paper set out to bring together what is known about when the technique is used, how it is performed, its role in meniscal surgery, osteotomy and knee replacement, its possible complications and its reported outcomes.
How was it done?
This is a narrative review; no new patient data were collected. The authors searched PubMed using the keywords "pie-crusting" and "knee". The results were screened by three experienced knee surgeons, and the selected studies were grouped under technique, indications, complications and clinical outcomes. The level of evidence is given as Level V, expert opinion.
What did it find?
- When? It should be considered when adequate view or working space in the inner compartment cannot be achieved despite standard manoeuvres. Because natural ligament laxity varies between people, the decision should be made during surgery. A working space that lets a probe pass comfortably is usually considered enough.
- How? The most widely accepted method is gradual puncturing of the superficial MCL from outside with a needle, under arthroscopic view. According to the review, needle size does not appear decisive; the number of punctures seems more important.
- Meniscal surgery: The authors propose a stepwise release, moving from the posterior oblique ligament to the deep MCL and finally the superficial MCL. Studies they cite report an increase in inner joint space of about 1.9-5.7 mm, with side-to-side differences generally within 0-1.1 mm.
- Osteotomy: In realignment surgery around the knee it is not routinely needed and may be considered in selected cases where inner tightness persists despite bony correction.
- Knee replacement: The technique is one of several used for ligament balancing; authors differ on the amount of tightness for which it is recommended.
- Complications: Those reported are generally mild and temporary: pain along the needle track, minor bruising and temporary nerve irritation. The main theoretical concern is over-release and instability; the studies cited did not report clinically relevant lasting instability with controlled use.
The authors' conclusion
The authors describe pie-crusting as a simple and widely used technique for controlled release of the inner soft tissues in a range of knee procedures. Applied gradually and according to the indication, it can improve the view, make instrument use easier and reduce the risk of surgical cartilage injury, without causing clinically significant instability in most cases. Its role differs between meniscal repair, osteotomy and knee replacement, so it should be tailored to the goals of each procedure rather than used routinely.
Limitations
- This is a narrative review, and its level of evidence is expert opinion.
- The authors note that the current evidence is largely based on retrospective studies with differing methods, and that randomised controlled trials are lacking.
- Long-term data on joint mechanics and the progression of osteoarthritis are limited; questions such as meniscal extrusion and how the ligament heals have not yet been studied systematically.
Reference
Şahbat Y, Akçaalan S, Güzel A, Turan K, Gürsoy S. (2026). The pie-crusting technique in knee surgery: Indications, technique, complications and outcomes. Journal of Experimental Orthopaedics, 13(2): e70783. Licence: CC BY 4.0.
DOI: 10.1002/jeo2.70783
Free full text: PubMed Central (PMC13239262)
This article summarises a published scientific paper for general information; it does not replace an examination or a personal medical assessment. Please consult your doctor about your symptoms.
