TELD — Calcified Disc Herniation

Over time, some disc herniations calcify — mineral is laid down within the fragment until it becomes hard, sometimes merging with the bony rim of the vertebra or forming a bony spur. A calcified fragment presses on the nerve just as a soft one does, but it behaves very differently under the endoscope: it cannot simply be pulled away, because it is anchored and rigid. Distinguishing a calcified from a soft herniation before surgery — usually on a CT scan, which shows bone clearly — is an important part of planning, because it changes the operation.

Here the surgery shifts from a soft-tissue task to a bone-working one, and this is where technique and instrument control matter most. Rather than grasping the fragment, I use a fine endoscopic burr and specialised instruments to carefully thin and take down the calcified material a little at a time, freeing the nerve gradually and working always from the safe side, under continuous magnified vision and irrigation. A controlled foraminoplasty — trimming the edge of the facet joint — often creates the room needed to approach the hard fragment along the right line. The pace is deliberate: the aim is to remove enough of the calcified mass to decompress the nerve fully while protecting it and the surrounding structures throughout. Decompression is confirmed when the nerve is seen to lie free and pulse normally.

I am candid with patients that a calcified disc is a harder operation than a soft one, whatever the approach. Working a burr close to a compressed nerve, in a confined space, demands precise control and experience; the margin for a slip is smaller, and the operation typically takes longer. This is precisely the sort of demanding case that endoscopic subspecialisation exists for, and it is where careful patient selection, thorough planning from CT and MRI, and refined instrument handling come together. It is also honest to say that, in some calcified cases, an open or alternative approach may be the safer choice, and part of my job is to make that judgement openly with each patient rather than force an endoscopic route where it does not fit.

The endoscopic treatment of calcified discs is increasingly well documented. A systematic review and meta-analysis of discectomy for calcified herniation has drawn together the techniques and outcomes, and comparative studies — for example of the interlaminar versus transforaminal endoscopic routes at the L5/S1 level — show that calcified fragments can be removed endoscopically with good results, using burrs and, in some centres, ultrasonic bone instruments. Series specifically describing endoscopic techniques for hard and calcified discs report favourable outcomes in experienced hands, while consistently noting the greater technical demand and longer operating time compared with soft discs. This honest picture — good results, but a harder operation requiring experience — matches my own approach to counselling patients.

When a calcified fragment is fully addressed, relief of the leg pain follows as the nerve is freed, and because the approach still spares the muscles and much of the bone, recovery is generally quicker than an equivalent open operation — often home the same day or the next. It is fair to expect that a calcified case may take a little longer to recover from than a straightforward soft disc, and that some temporary nerve sensitivity can occur early on and usually settles. Numbness and long-standing weakness may take longer to recover and do not always resolve fully. The spine is followed up over the longer term.

• —Kang J, et al. Surgical techniques and outcomes after discectomy for calcified lumbar disc herniation: systematic review and meta-analysis. (PMID 37659048)
• —Cheng YP, et al. Percutaneous endoscopic interlaminar versus transforaminal discectomy for L5-S1 calcified disc herniation. (PMID 35279101 / PMC8917767)
• —Cheng YP, et al. Percutaneous endoscopic interlaminar discectomy for L5-S1 calcified lumbar disc herniation. (PMID 36211293 / PMC9537603)
• —Transforaminal endoscopic discectomy for hard/calcified lumbar disc herniation: technique and outcomes. (PMID 32712402)
• —Endoscopic-matched ultrasonic osteotome for removal of calcified lumbar disc herniation. (PMID 31718310)
• —Ruetten S, et al. Full-endoscopic interlaminar and transforaminal versus microsurgical lumbar discectomy (RCT). (PMID 18427312)
• —Gadjradj PS, et al. Full-endoscopic transforaminal versus open microdiscectomy: systematic review and meta-analysis. (PMID 35867477)