GB2517672A - A programmable alignment jig for orthopaedic surgery - Google Patents

Abstract

A drilling, cutting, reaming or sculpting guide is positioned onto bony or cartilage-covered bony surfaces to conform to the surface. The guide is provided with connecting parts 10 which receive spacing components 7 so that the guide seats onto the bony surface in a preplanned and customised, patient-specific manner, as determined by measurements or planning in computer software using three dimensional imaging data. The spacing components may be selected from a set containing components of incrementally different lengths, possibly with an increment of 0.5 mm. Alternatively the spacing components may be manufactured using additive or rapid prototyping techniques, or may be cut to length with a trimming tool (figure 7). The jig may be a programmable acetabular device 4 having apertures to receive spacing studs colour coded according to their length. A socket 5 in the jig may receive a guiding component GC part of a guiding assembly GA anchored to the ilium.

Description

A Programmable Alignment Jig for Orthopaedic Surgery In the course of orthopaedic surgical procedures holes may be drilled and the bone prepared in specific configurations and relationships for the purpose of screw insertion. joint replacement, and other bony surgical procedures where precise preparation of the bone is reqi nred.

Sometimes surgery is planned on the basis of 3 dimensional (3D) data derived from scanning/ imaging / modelling modalities, such as Computed Tomography (CT), Cone Beam Computed Iornograpliy (CBCT), Magnetic Resonance liriaging (MRI) or 31) optIcal scannmg teclniologies. Where tins sort of 31) dat;i is surgery may he planned in a virtual on-screen' environiiieni SO that for exairiple, the precise position ol a fur) jonit prostheses or knee joint prosthesis can be pre-planned. before surgery, accordingly to biometric principles and the perceived needs of die padenL Rapid Prolotyped (RB), paLienl specific physical culling guides, drill guides, or surgical jigs may then be manufactured to constrain and guide bony preparation, so that the virtual plan may be transferred to the surgical site. Alternatively, surgical navigation may be used to guide the surgeon at the time of surgery.

RB paliemil specific guides are currently available for joinL replacernenL surgery for the knee and hip and in other surgical situations including eg. the spine and the jaws. These patient-specific guides are typically made using additive manufacturing tecirnologies or other CAD CA2vi technologies. They are designed to fit precise or to a planned tolerance or level of precision, in a pre-planned configuration onto for example the spine, femoral head, tibia, or into the aceahulumn. l1ie lilluig sinlace is (lelimied by a 31) (lata ol the bony substrate, and orientation ol the guiding eleineni defined by preoperative planning iii software. using 3D volumneiric, or sonieinries 21). image data.

This approach to providing a guide for surgery has several disadvantages, notably: * Each guide needs to be specifically manufactured for each patient with resulting delays.

* Additive iriamiufacLunmig leclniologies are costly * Sterilization at high temperature may cause warpage * The guide needs to he sterilised, and in some clinics sterilisation must take place in specific locations and according to specific protocols that are not compatible with the inateria Is that have been used -and may cause lint icr delays to [real uen[.

I lowever. (lie great advantage of these RP patient specific gindes is (fiat inilike the generic guides that may sometimes he available for orthopaedic producers, they fit intiniarely against (lie patIent's anatomy, and perrint highly accnra Ic and predictable posi Ioinng and onentaLion.

The present invention relates to a surgical guiding device that may be modified or programmed' by the addition or subtraction of modifying accoutrements, such as pegs, studs, or screws or other suitable spacing components (SCs), which modify the fitting surface of the programmable jig so as to better fit the surgical site, and guide the surgical procedure according to a plan formulated by an associated software tool. The software tool will specify the type and position of the SCs, not only to achieve the best fit to the bony site, but also to align the guiding element of the device according to the planned orientation.

Said SCs may be non patient specific pre-manufactured components or may be patient specific manufactured using RP technologies, perhaps by a local 3D printer.

A specific embodiment of this invention will be described in the context of surgical preparation of the acetabulum in hip replacement surgery, with reference to figures 1-7.

Hip replacement or resurfacing operations are a common treatment for arthritic hip joints.

Revision replacements are also relatively conunon (10%) in view of the large nunibers of primary operations.

During the procedure a joint prosthesis is inserted, having femoral and acetabular components.

The longevity of the reconstruction and joint prosthesis, and the health of the surrounding tissues may be adversely affected by inappropnate positioning of the components of the prosthesis. leading to inappropriate mechanical loading, adverse wear and tear, loss or stability and biological complications.

Positioning problems are more often associated with the acetabular coniponent equally, correctly positioinrig the acetithular component appears to favour a longer lasting outcome, with ideal contact between femoral and acetabular components. and ideal load distribution and op[iinised wear oF 11w two paris.

Access to the acetabuluni is a somewhat invasive surgical intervention, particularly if the head of the femur is preserved, as with resurfacing' procedures. Without wide exposure of the area, it can be difficult to adequately orientate the prosthetic components. particularly the acetabular c()miIpoiIeiIt. I lowever, jR)sI-opera(]ve lieatnig and reFiabitila [ion is inproved by ininimnising surgical exposure of the acetahuhirn.

It is therefore desirable that any device intended to increase accuracy should not necessitate unnecessary exposure of the pelvis.

Various approaches including robotic or image guided navigation have been used in an attempt to improve spatial awameness and help to accurately position the prosthetic components. RP patient specific guides have also been used in this context.

Such techniques require preoperative planning using eg.3D imaging of the pelvis to plan an ideal' position for die acetabular component, but rely upon die availability of sophisticated apparatus.

Rapid prototyping / additive manufacturing / CAD C;Ui production, to fabncate a bone supported cutting or patient specific drilling guide (RPG) are not readily applicable to the acetabulum. because in order to seat a rapid prototyped guide over die acetabulum for preparaLon of die acelabulun, as it is the acelabuluin iiself. which needs lo be prepared for the prosthesis.

Fignre 1 shows die aceiahnniii and adiaceiir snrfaces, i icludi ig (lie iliniti of ilie pelvis (1). die nilenor niargm ol (tie tine floor ol [tie aceizhiiliiiri: coivloid lossa; and various paris of die acelabularrini (P) and die acetabular noLch (2).

Fignre 3 shows Iio)w Ellis issue iria he dealt with by using ilie RPG (3) to innisier a guiding relationship to an additional guide (4) anchored into the Ilium, or other mechanically stable frame of reference Lo form a Guiding Assembly' (Gk). After die correci orientation has been Lraimsfened to die GA, die RPG can be removed from die acelabulum to allow access to die acetabulum for reaming and implantation as in figure 3. The fixated GA is then, in turn, used to achieve accnrate surgical preparation of the acetabulum and implant positioning to the planned position.

In dus contexL tius embodiinenL provides for a programmable acetabular device (PAD). which takes the place of the 112G.

An emribodimrieni ol (ins i ivenilori will miow he described with reference to figures 4 -7 diougli many iiera [ions of ibis device in general Form, ca tibia [ion, and design and conligiiration of die SCs is envisaged.

Imaging and software planning 3D imaging, eg including but not restricted to Computed Tomography (CT), Cone Beam Computed Tomography (CBCT). optical scanning, and magnetic resonance imaging (MM) may be nsed to generate a 3D dataset of the pelvis which is viewed in an on-screen virtual environment. The software will include access to a library of prostheses, which may be generic in form or manufacturer specific.

The method provides for dedicated software having visualization, modelling, measurement, and computer aided design (CAD) ifinctionality.

The software enables die segmentation of die data seL. with die production of aim on-screen 3D niodet, e.g. by surface or volunie rendenng, derived from die dab set, by assigiung a dueshiotd value to the data.

The software enables die planning of the optimal position of the Acetabula Component (AC) of a joint prosdiesis in tenns of axis. ajigulation, and depdi to be planned. e.g. with respect to the anterior and transverse pelvic planes.

having esiabhslied a possible position br die AC of ilie joint prosthesis, [lie snrgeon (or other operaior) is ilien able io i idicai.e on screeii ihe exieni. of the proposed snrgical exposure of die acelabuluin (Figure 1) and adjacent surfaces, including die ilitnn of die pelvis (1), die inferior margin of die Irue floor of the acelabuluin; coLyloid fossa; and various pafis of the acelabular rim (P) and the acetabular notch (2).

Tins deliiies (lie peririeLer of (lie surgical exposure; wi(iun (Ins permie(er, aL operation, (lie surgeon will have access to (lie siirlace oF (lie aceLibiilinn. with po(eiiha 1 exteiisi()n ori(o (lie ilium and die acelabular noich.

Generating a specification for the PAD

ihie soflware will eveniiia liv use [lie suriace data and described perineter to crea Ic a digiLi

specification for die PAD.

The PAl) hasageneric struchire having a body (4) diaL ills wi(iiin the aceLhnlumn. l)iflerent.

sized PAD's al-c available, so as lo be able Lo achieve die closesi possible besi' fiL for die body of (lie PAl), along wilhi (lie necessary SCs. The soliware will allow an appropria(elv sized PAl) to be selected from the PAD library. such that it will fit within die defined perimeter, appropriately apprxniia (ed to (lie aceLibn ar snrface.

itie body of the PAl) (4) niay mIce a number of forms, ranging from a skeletal object that may Or may noi lit, iii conL ct. with a few carefully delined poinL widun the aceLibu miii and aroinid the perimeter, or, it may be more robust and bulky. The perimeter of the pad may be selected to fit witlun the perimeter of the acetabukun.

The PAD is designed Lo include fealures which will be undersLood wiihin die associaled software, and possibly also visible on-screen, to allow die guiding assembly (GA) (figures 2 and 6) to be set up as described above. The goal is diat die PAD is only temporarily fitted into place, but has features that permit the drill guide element of the remotely' anchored GA to be oriented such diat it does not interfere with preparation of die acetabulum.

In (Ins eiubodinien, there is a recess (Figure 6, (4) in (lie depth of die pan ol (lie PAL) (ha t. IlL into the acetabukuu. This recess has a standardised configuration, such that a standard Guiding Component (GC) may be precisely seated within the recess. The position of the GC is intended to reflect the optimum vector for die mechanical preparation of the acetabulum.

Furtherniore, suitable markings along the length of the GC. which may correspond to markings on the instrumentation used to prepare the acetabulum, may indicate the ideal depth for the prepara tjoi i.

The intention is to orientate the PAD such that the CC is correctly orientated to guide surgery such (haL (lie i nplant. is correctly k)ca ted.

The orientation of the PAD is intended to be determined by automated or manual selection of appropriately selected spacing components (SCs), such that when the correct components (e.g. 7) are fitted e.g. into recesses in the guide (e.g.8). the PAD is orientated in a pre-planned orientation (and so too therefore are the CC and therefore die GA orientated in a pre-planned orientation).

In other situations and embodiments, e.g. the preparation for a knee prosthesis, it is only the direct seating of the programmable guide that may be relevant A recess (9) at die base of die PAl) is planned such diat die bony base of the acetabulurn may be visualised and explored with an instrument by removing the CC, so as to be able to verifr die fit of the PAD against die bony surface, and this will be an advantage of more skeleutl designs, in that. the contact between the SCs and the bony base and perimeter may be visualised or explored with a graduated probe.

Anti-rotational feauires, e.g a rod (12) of a length and position defined by software to lit into die acetabular notch Ilius at the time of surgery, the PAl) may be positioned with a normal, exposure of die site, save perhaps for slight extension on to die ilium and beneath die transverse acetabular ligament. With the PAD in place, die sealing of die PAD niay be verified before die GC is inserted.

This embodiment provides for a standardised system of PAD's which have a general configuration to fit. a range of differently sized acerabulae -that is die main body is available in a range of different sizes.

An appropriately sized PAL) is selected from the range available, to fit within the acetabuhim such dial. the planned central access of die future acetabular prosdiesis lines up with the central axes of die jig, leaving a small space between the jig and the patient acetabuluin.

Ibis process is facilitated within die associated software application, which enables a library of components to be tried in the virtual environment onto a segmented virtual model of the patient's acetabulurn.

Selecting the spacing components In diis embodiment each of die PADs contains a number of recesses (along that surface which faces die acetabuhmi, and along spokes' (10), which protnicle radially from die PAL).

The recesses are designed to finnly retain a range of studs' (11), which may be pressed into die jig, These studs also act as spacing components. Together, the spacing components will alter the relationship between the PAD and the acetabulurn, by selecting studs or similar componets of different sizes.

The specification for these components is derived froni an associated software program which will generate a specification for the PAl), and a specification for length and position of cacti of the spacing coinponenis. For example. a particularly sized PAD. aiid coiour coded slud available in 0.5mm increments.

In (Ins way, (lie acetabular jig may he prograiruried' to Ii( mb (lie acetahuluiri wili a plaiuied onenLQou. BY alteniig (lie size ol (lie spacuig coiriponenL, (lie oneut;ihon of IIie PA!), and therefore of the associaled C-C may be allered in sinai!, known. and cinincally televauL mcreuiieiiLs.

Other Embodiments Other embodiments of this inveiition would provide for Programmable Devices that fit other aim (ohilica I regions, perhaps reqnirnig (hUerent SCs, (o kri a ci (;ilogue ol Progranur able (,nides. and range ol sjnci ig coiriponeuts.

Spacing components may take many generic forms and configurations, may bc designcd to fit the particular anatomy that they will encounter, eg a \T' shape to more firmly locate onto a rim, or a poui( (o penetra be (jssue.

Spacing components may be mass produced and disposable or reusable, available in a range of incremcnts. or may bc made using IRP technologies, using a specification / design output from the associated software. Such RP SCs may he used alone or in combination with generic SCs.

The embodiment illustrated in figure 7 is provided with radiating. graduated spokes. These may be trimmed according to a specification defined by the software, with an associated (unnnng tool. Associa (ed wi(h (lie spokes, there may also he provided cvlindrica 1 sleeves of different lengths and diameters which may he pressed firmly over the spokes, to extend the PA!) to (lie pen ne(er ol (lie aceLiblilinu, and widen (lie spoke, to Like lii) the space he(weeu the spoke and the bony perimeter.

Al(ernaQvely sleeved s(iids iiiay he previded (o elongate as well as widen (lie spokes

Claims (4)

1. Claims 1. Adrilling, cutting, reanung or sculpting guide, u' physical platlbrin fbi interface »=uid uansfhr between patient and a virtual environment, which is positioned onto bony or cartilage-covered bony siirthces to conform to the bony surface. Said ginde is provided with connecflng paits, which act as spacing components so that the guide seats onto the bony surface in a preplanned and predesignated manner, as determined by measurements or planning in computer software.
2. 2. A drilling, cutting, reaming or sculpting guide, or physical platfbrm for interface and transfer between patient and a virtual environment, which is positioned onto bony or cartilage-covered ixiny sinlaces to conlonn to the bony surface. Said guide is provided with coilllecl]ng parts, which ac.t as spacing conipoucus so that the guide seats onto die bony surf ilce in a preplaiumd and predesiguated manner, as determined by measurements or planning in associated computer software.
3. 3. A guide as described in the previous claim where the position of the guide is planned using computer software to describe or dictate adjustments to the ginde, or connected components, so dial it will beth conlorin to the bony surlace to which it is--dI)I)li(cl.
4. 4. A guide as described in previous claims, where specific orientation is dictated by spacing components.:. A giude as described u] previous claims, where orientation s dictated by spacing components., where the spacing components arc prescribed by measurements made i'm associated software 6. A guide as described in the previous claim, where orientation is dictated by a prescnptton for die comimiecleci conipomiemils generated 1w associated conipulr soltware 7. A guide as described in previous claims in which computer software, or measurements taken from coniputer soltware (lesem he a type and size ol spacu]g comttponenls which lit between die guide aud the bony sumhitce so as to transf hi a virtual smgical plan to the surgical site.8. A surgical guide as described in the previous claim where the size, position, and type of spacing components positioned into, onto, or between the guide and the bone is dictated by sofiware or measurements taken floin tIme patients anatonmy.9. The system of surgical guides as described above, excepting that in this case spacing comnpom]emlts are mttade using mapid protolypilig (i.e. $1) pnm]li g, additive rmlamlt]factu]im]g, milling teclimiiques) 1<) closely adapt Lie gmude to die bony site.10. A system of guides as described in previous claims which are sized incrementally to cope with of different individuals, all with connectivity for spacing components so that software can select the guide body, and choose appropriate spacing components such that the guide better fits die bony snrface, and that there is sufficient space available between die main body of the giude and the bony surface to permit optimal positioning, and also orientation of the guide.I I. A guide, or syslrn of guides n]lended for use logel icr wit 1i surgical plam]ui ig software, wI iere die software provides a patient specific prescription for adjustment, alteration, or adaptation of the surgical guide to allow the surgical procedure to be correctly orientated to allow replication and transfer of the softwam planning to the surgical site.12. A programmable guide, substantially as described in the accompanying description and drawings.S