9Bone Cement Ossiculoplasty for Short Defects

FFilling the gap instead of replacing the chain

The single commonest ossicular injury in chronic ear disease is erosion of the long process of the incus. Its blood supply is the most tenuous in the chain, so cholesteatoma, recurrent infection and even a retraction pocket nibble away its tip and lenticular process while the rest of the chain — the malleus, the incus body, and crucially the stapes superstructure— stays intact and mobile. What remains is a small gap: a millimetre or two of empty space between the stump of the incus and the head of the stapes, across which sound can no longer pass. The result is a conductive hearing loss out of all proportion to how little tissue has actually been lost.

The conventional answer is to discard the eroded incus and bridge the gap with a prosthesis, or to sculpt an autograft incus and interpose it. Bone-cement ossiculoplasty asks a different question: if the defect is small and the rest of the chain is healthy, why not simply fill the gapand re-link what is already there? A paste of biocompatible cement is moulded across the space, sets to a solid bridge, and re-establishes continuity between the residual incus and the stapes — no prosthesis, no foreign implant to extrude, and the patient’s own ossicles still doing the work [2004]. This is reconstruction by addition rather than replacement, and for the right defect it is elegant, quick and cheap.

The technique is sometimes called incudostapedial rebridging, and the phrase captures both its strength and its boundary. Cement is superb at re-bridging a short incudostapedial gap with an intact mobile stapes; it is a poor substitute for a whole missing ossicle or a long, load-bearing span. The whole module turns on that distinction: cement is a gap-filler for short defects, not a universal reconstruction[2005].

FThe cements: hydroxyapatite versus glass-ionomer

Several materials have been tried as middle-ear cements over the decades, but two families dominate the story, and understanding their chemistry explains why modern practice has settled where it has.

Hydroxyapatite (HA) cement is a calcium-phosphate paste whose mineral composition closely resembles natural bone. It is osteoconductive— bone and fibrous tissue integrate with it rather than walling it off — and it is biologically inert in the middle ear, with no reported neurotoxicity. It mixes to a workable paste, gives the surgeon several minutes of working time, and then sets to a firm bridge. These properties have made HA cement the material of choice for ossicular rebridging[2005].

Glass-ionomer cement (GIC) entered otology with real advantages: it bonds adhesively to bone and sets reliably. But its chemistry carries a hidden danger. As it sets it releases aluminium and fluoride ions, and aluminium is a potent neurotoxin. The decisive warning came from reports of fatal aluminium encephalopathy after otoneurosurgical use of ionomeric cement placed in contact with cerebrospinal fluid; these led to withdrawal of the cement from neuro-otological use[1994]. The lesson is precise rather than absolute: glass-ionomer must never contact CSF, open dura or a breached tegmen. Confined to the ossicles in an intact middle ear it has been used safely in some hands, but the safety margin is narrow and the consequences of error catastrophic, which is why HA cement is now strongly preferred. Older calcium-phosphate compounds such as Dahllite, troubled by handling and inflammatory concerns, never gained a foothold.

TWhen cement is the right tool, and when it is not

The indication is narrow and worth memorising. Bone cement is at its best for a short incudostapedial defect — typically a gap of one to two millimetres — where the stapes superstructure is present and mobile and the residual ossicles sit in reasonable alignment. The classic scenario is an eroded incus long process with an intact stapes: the chain needs only its broken link mended, and cement mends it without sacrificing the parts that still work [2004].

The boundaries are defined by what cement does badly. The first is span length. When the gap is long — for example a malleus-to-stapes reconstruction across an absent incus — a cement bridge becomes a slender, brittle, unsupported beam that is prone to fracture under the repeated micro-loading of a working middle ear. A direct comparison of incus-to-stapes against malleus-to-stapes cement bridges found the short incus-to-stapes bridge the more reliable, and pushed the longer span toward a prosthesis [2005]. The second boundary is an absent stapes superstructure: there is then nothing for the bridge to rest on, and the defect demands a total ossicular replacement prosthesis from the footplate, not cement. Beyond a few well-chosen revision-stapedotomy uses — augmenting a tapered incus, or locking a crimped piston to an eroded incus — cement is not a general-purpose reconstruction [2005].

A reconstruction philosophy emerges that several large series share: reserve cement for short defects with a mobile stapes, and reach for a prosthesis when the gap is long or the superstructure is gone[2015]. Like every ossiculoplasty, the result also depends on the ear it is done in: a dry, well-aerated middle ear with healthy mucosa gives cement its best chance, and a wet, atelectatic or actively diseased ear undermines any reconstruction regardless of material [2001].

TThe technique: a dry, shielded, short bridge

Cement is unforgiving of a sloppy interface, and almost every failure traces back to one of a handful of avoidable errors. The sequence below distils the published technique.

• Confirm the defect.A short gap, an intact mobile stapes, well-aligned ossicles — the indication, checked before any cement is opened.
• Dry and de-epithelialise. Cement bonds only to dry, mucosa-free bone. Remnant mucosa and moisture are the commonest causes of a weak bond, so the incus stump and stapes head are cleaned and dried before application [2015].
• Shield the footplate.Antibiotic-soaked gelfoam is laid over the footplate and round window so that no cement spills onto the footplate — which would fix the stapes and abolish the very mobility the operation depends on — or onto the round-window membrane. Keep all cement away from any exposed dura or CSF[1994].
• Sculpt the bridge. The paste is moulded across the gap to re-link incus to stapes head, using the several minutes of working time to contour it precisely while supporting the ossicles against drift[2005].
• Let it set, then test. The cement is left undisturbed to harden (on the order of five to ten minutes), the shield is removed, and a continuous mobile chain is gently confirmed.

Two principles run through the whole sequence. The interface must be dry and clean, because cement cannot bond through mucosa or fluid; and the footplate must be protected, because a drop of cement in the wrong place converts a hearing-restoring operation into an iatrogenic fixation. Done carefully, the reconstruction leaves the native chain intact with nothing foreign load-bearing in the middle ear.

CWhat the outcomes show

For its narrow indication, bone cement delivers results on a par with the alternatives. Across the published literature, air-bone gap closure to within 20 dBis achieved in roughly 70–90% of cases when cement is used for a short incudostapedial defect with an intact mobile stapes — the same range one expects from incus interposition or a PORP for the same defect [2011, 2004]. A systematic review pooling eleven studies put ABG closure within 20 dB at 60–94%, with mean gap closure of roughly 15–23 dB [2015].

The honest summary is one of equivalence, not superiority. That same systematic review concluded that, while cement clearly does not underachieve compared with conventional rebridging, the evidence does not establish it as superior either [2015]. In other words cement earns its place as a legitimate, often more convenient option for the short-defect ear — faster, cheaper and prosthesis-free — rather than as a uniformly better one. Reassuringly, large HA-cement series report no meaningful extrusion or delayed foreign-body reaction when the material is confined to dry ossicular surfaces under controlled conditions [2004, 2015].

CPitfalls, safety and where cement sits in 2026

The complications of bone-cement ossiculoplasty are nearly all preventable and nearly all flow from breaking one of the rules above. A weak bond comes from applying cement to a wet or mucosa-coated surface, and re-erodes into a recurrent gap. Stapes fixationfollows cement creeping onto the footplate, and turns a conductive gain into no gain at all — which is exactly why the footplate is shielded. A fractured bridge is the price of building too long a span, which is why cement is reserved for short defects. And the gravest hazard, aluminium neurotoxicity, belongs specifically to glass-ionomer cement in contact with CSF or open dura; it is avoided by preferring HA cement and by never letting any cement near a breached tegmen or dural defect [1994].

Where does that leave cement in current practice? It is a focused, valuable technique rather than a first-line replacement for prostheses. For the specific and common problem of an eroded incus long process with an intact mobile stapes, an HA-cement bridge restores the native chain quickly and without an implant, with hearing results that match the alternatives [2015, 2011]. It also has a useful niche in revision stapedotomy, where a thinned or eroded incus can be augmented or a loose crimp secured with a touch of cement [2005]. The discipline that makes it work is the same discipline that defines its limits: a short defect, a mobile stapes, a dry shielded interface, and a cement — hydroxyapatite, not glass-ionomer near CSF — that the middle ear will tolerate for life.