Glenoid Bone Loss in Primary Total Shoulder Arthroplasty ... · Glenoid bone loss has been shown to...

Glenoid Bone Loss in PrimaryTotal Shoulder Arthroplasty:Evaluation and Management

Abstract

Glenohumeral osteoarthritis is the most common reason forshoulder replacement. Total shoulder arthroplasty provides reliablepain relief and restoration of function, with implant survivorshipreported at 85% at 15 years. Glenoid component wear and asepticloosening are among the most common reasons for revision.Glenoid wear characteristics have been correlated with, amongother things, the degree of anatomic glenoid version correction.Anatomic glenoid reconstruction is particularly challenging in thepresence of glenoid bone deficiency. Walch classified glenoidmorphology into five types: type A, centered, without posteriorsubluxation but with minor erosion (A1) or major erosion (A2); typeB, posteriorly subluxated (B1) or posteriorly subluxated withposterior glenoid erosion (B2); and type C, excessive glenoidretroversion. The type A glenoid represents only 59% of patients;thus, the need to address glenoid deformity is common. Methodsof correction include asymmetric reaming of the anterior glenoid,bone grafting of the posterior glenoid, and implanting a specializedglenoid component with posterior augmentation. In many cases oftype C or hypoplastic glenoid, the humerus is concentricallyreduced in the deficient glenoid and glenoid deformity may notneed to be corrected. Severely hypoplastic glenoid may require theuse of bone-sparing glenoid components or reverse total shoulderarthroplasty.

The rate of total shoulder arthro-plasty (TSA) continues to in-

crease in the United Sates, with ap-proximately 20,000-25,000 surgeriesperformed annually and doubling infrequency approximately every 7years.1 Osteoarthritis (OA) remainsthe most common indication forshoulder replacement, and in 95% ofthese patients, shoulder arthroplastyis associated with pain relief, im-proved function, and patient satis-faction.2 Although implant survivor-ship is estimated to be >85% atminimum follow-up of 15 years for

most commonly used prostheses,3 ameta-analysis of long-term studiesdemonstrated the revision burden tobe approximately 7%.4 Glenoidcomponent failure (ie, aseptic loosen-ing) is the most common complica-tion following shoulder replacementand accounts for most unsatisfactoryresults.2 Factors that contribute tocomponent loosening include alteredjoint reaction forces, componentmalposition, and insufficient bonysupport of the implanted glenoidprosthesis.2-4

Glenoid component malposition-

Benjamin W. Sears, MD

Peter S. Johnston, MD

Matthew L. Ramsey, MD

Gerald R. Williams, MD

From Thomas Jefferson UniversityMedical Center, The RothmanInstitute, Philadelphia, PA.

J Am Acad Orthop Surg 2012;20:604-613

http://dx.doi.org/10.5435/JAAOS-20-09-604

Copyright 2012 by the AmericanAcademy of Orthopaedic Surgeons.

Review Article

604 Journal of the American Academy of Orthopaedic Surgeons

ing increases stress forces across thecomponent and is a common reasonfor failure. In their analysis of 80successful and 53 failed TSAs,Moskal et al5 found no instances ofassociated glenoid malversion amongthe successful replacements. How-ever, 46% of the failed TSAs werefound to have glenoid componentmalversion. Shapiro et al6 demon-strated that placement of the glenoidin 15° of retroversion significantlydecreased the glenohumeral contactarea (P < 0.0002), increased contactpressures (P < 0.0002), and de-creased inferior and posterior gleno-humeral forces (P < 0.02 and P <0.03, respectively), in cadaver speci-mens. This raises concern for long-term component viability. Farronet al7 used finite element analysis toevaluate torque at the cement-boneinterface with increasing degrees ofglenoid retroversion. They reportedan increase in micromotion at thecement-bone interface of >700% andstress increase of 326% with compo-nent retroversion >10°. The authorsconcluded that glenoid retroversion>10° should be corrected and that, ifversion correction is not possible, thesurgeon should consider not per-forming glenoid resurfacing. Al-though controversy remains regard-ing the effect of glenoid malversionon implant longevity, the reportedbasic science and clinical literature todate support restoration of normalglenoid version as a means of im-proving component durability.2-7

Glenoid bone loss has been shownto contribute to glenoid componentmalpositioning and loosening sec-

ondary to inadequate bone supportand incomplete component seating.7,8

In addition, the use of asymmetricreaming to manage glenoid bone lossresults in reduced amount of boneremaining for fixation, which putsthe patient at risk of glenoid vaultpenetration. Unrecognized corticalpenetration can result in cement ex-trusion. In addition, unless the fixa-tion device (ie, peg, screw, flute, keel)gains purchase of the perforatedvault, the initial fixation is likely tobe compromised. Uncorrected boneloss may also result in insufficientseating at the periphery of the gle-noid component, creating the poten-tial for eccentric loading of the im-plant and increased stress levels atthe implant-bone interface.

OA alters glenohumeral biome-chanics and modifies the anatomicfeatures of the glenoid. Over time,these changes result in increased pe-ripheral glenoid contact stresses andposterior glenoid bony erosion, lead-ing to increasing glenoid retroversionand posterior decentralization of thehumeral head from the socket. Thesefindings are common in glenohu-meral OA and are seen in up to 40%of patients with advanced disease.9

These anatomic changes add to thetechnical difficulty of correct glenoidcomponent implantation and affectthe longevity of the implant.

In 1999, Walch et al9 examined113 axillary CT scans of arthriticglenoids and developed a classifica-tion system based on wear patternsand version (Figure 1). This classifi-cation has become the most com-monly used to describe glenoid

morphology. Type A glenoid mor-phology, which was seen in 59% ofpatients, consisted of a centered hu-meral head in the socket, with aver-age glenoid retroversion of 11.5°.These patients were subclassified bydegree of glenoid erosion, whetherminor (A1) or major (A2). Type B,the next most common glenoid mor-phology, was associated with poste-rior subluxation of the humeral headand asymmetric joint force distribu-tion. Type B1 morphology is charac-terized by a narrowed posterior jointspace and lack of posterior erosion.Type B2 is characterized by posteriorerosion and an associated biconcaveappearance (Figure 2). Type C gle-noid is hypoplastic, with retrover-sion >25°.

Types B2 and C demonstrate themost advanced changes in glenoidmorphology and are the most diffi-cult to manage. To effectively treatthese patients, the surgeon must havea thorough understanding of the de-gree of anatomic change, includingretroversion, degree of bone loss,and amount of humeral head dis-placement. Advanced diagnostic im-aging, notably three-dimensional(3D) reconstruction CT, is an impor-tant tool to evaluate glenoid bonestock and version.10,11 Surgical man-agement of glenoid retroversion andbone loss depends on severity. Themost common method to correct ver-sion involves eccentric reaming ofthe anterior glenoid, or high side, toa more neutral version. However,with significantly increased versionor bone loss, this method can resultin removal of a substantial amount

Dr. Ramsey or an immediate family member has received royalties from, serves as a paid consultant to or is an employee of, andhas received research or institutional support from, Integra (Ascension), and serves as a board member, owner, officer, or committeemember of the American Academy of Orthopaedic Surgeons, the Philadelphia Orthopaedic Society, the Rothman Institute, and theRothman Specialty Hospital. Dr. Williams or an immediate family member has received royalties from, is a member of a speakers’bureau or has made paid presentations on behalf of, and serves as a paid consultant to or is an employee of, DePuy; has receivedresearch or institutional support from Tornier; has stock or stock options held in InVivo Therapeutics; and serves as a board member,owner, officer, or committee member of the American Shoulder and Elbow Surgeons and the Pennsylvania Orthopaedic Society.Neither of the following authors nor any immediate family member has received anything of value from or has stock or stock optionsheld in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Sears and Dr. Johnston.

Benjamin W. Sears, MD, et al

September 2012, Vol 20, No 9 605

of bone. In these cases, either bonegrafting or use of an augmentedcomponent may be required. Recog-nition and management of alteredglenoid morphology and diminishedbone stock are important for success-ful shoulder arthroplasty.

Preoperative Evaluation

Preoperative planning is essential tomanage bone deficiencies and defor-mity correction in TSA. Althoughplain radiographs continue to be thestandard diagnostic modality, multi-axial 3D imaging has enhanced theinterpretation of bony architecturalchanges associated with shoulderOA. In patients with posterior ero-sion, CT provides the most definitiveevaluation of glenoid version, vaultanatomy, and severity of boneloss.10-13 This assessment is helpful indetermining whether the use of astandard glenoid prosthesis is feasi-

ble or glenoid augmentation is re-quired.

Standard radiographs are necessaryfor preoperative planning. AP, trans-scapular lateral, and axillary lateralviews should be obtained. The APradiograph, which is often per-formed in internal and external rota-tion, is used to assess bone quality,note the presence of osteophytes, anddetermine the diameter of the hu-meral canal. The axillary view pro-vides information on posteriorglenoid wear and subluxation. How-ever, the axillary view has beenshown to overestimate retroversionin up to 86% of patients.12

Early descriptions used CT scansto accurately characterize the anat-omy and version of both nonarthriticand arthritic glenoids.12-14 Friedmanet al13 were the first to use CT tocharacterize the association betweenglenoid retroversion and OA. Theyintroduced a method to calculate gle-

noid version using the transverse axisof the scapula, defined as a linedrawn from the tip of the medialborder of the scapula to the mid-point of the glenoid fossa. Randelliand Gambrioli14 also proposed a

Illustration of the Walch classification of glenoid morphology, which is based on wear patterns and version. A, Type A1,centered humeral head with minor glenoid erosion. B, Type A2, centered humeral head with major glenoid erosion.C, Type B1, posterior subluxation with no erosion. D, Type B2, posterior erosion with a biconcave glenoid. E, Type C,severe retroversion.

Figure 1

CT scan of a type B2 glenoid. Notethe biconcave glenoid surface andapproximately 50% posteriorsubluxation of the humeral head.

Figure 2

Glenoid Bone Loss in Primary Total Shoulder Arthroplasty: Evaluation and Management


technique that uses the scapularbody line to calculate glenoid ver-sion. In both of these methods, a linedrawn perpendicular to the axisalong the glenoid surface was de-fined as neutral version, and the an-gle from either the posterior marginor the anterior margin of the glenoiddefined the native version (retrover-sion and anteversion, respectively)(Figure 3). More recently, Rouleauet al15 characterized the glenoid sur-face with eccentric wear using threenew reference lines: the paleoglenoid(original glenoid surface), intermedi-ate glenoid (line from anterior and

posterior edge), and neoglenoid (pos-terior erosion surface) (Figure 4).These authors determined that thecombination of the Friedmanmethod and the intermediate lineprovide the most reliable determina-tion of glenoid version in the pres-ence of posterior wear. However, al-though CT is the most accuratemodality with which to assess gle-noid version, measurements of ver-sion have been shown to vary by asmuch as 10° with only minorchanges in scapular rotation in thecoronal plane.16

Recent work has demonstrated thevalue of 3D CT to accurately charac-terize glenoid morphology comparedwith standard two-dimensionalCT.10,11 Scalise and colleagues10,11

have published extensively on theutility of 3D CT in preoperativeplanning and have developed soft-ware to estimate physiologic glenoidversion in patients with severe OAand deformity with a glenoid vaultmodel. At our institution, 3D CT isordered for patients with radio-graphic evidence of combined gleno-humeral subluxation and posteriorglenoid erosion. Three-dimensionalreconstruction with humeral or scap-ular subtraction is useful to furthercharacterize bony anatomy in casesof severe deformity and can providea template to fabricate a referencemodel for preoperative planning andintraoperative use.

Eccentric Reaming

The goals of glenoid resurfacing in-clude correction of version and pro-vision of adequate bone to supportthe implant. The most commonmethod to correct version involveseccentric reaming of the anterior gle-noid to the level of the posterior sur-face to recreate glenoid version andre-center the humeral head. Thistechnique effectively creates a new

neutral articulation between the gle-noid implant and the humeral im-plant, with the aim of providing con-gruent contact between the bone andthe glenoid prosthesis (Figure 5).Cannulated reaming systems allowplacement of a guide pin to assessplanned version correction beforereaming. These have become popularto help guide reaming in the correctversion.

Although eccentric reaming is com-monly used to address minorchanges in glenoid version, there areno clear guidelines regarding theamount of glenoid erosion that cansafely be corrected with this method.Severe retroversion requires the re-moval of increasing amounts of ante-rior bone, thereby creating a moresevere glenoid deficiency. This canlead to insufficient version correctionand placement of the glenoid compo-nent in residual retroversion. The im-portance of version correction wasdemonstrated by Lazarus et al,17 whoreported that insufficient version cor-rection was the most common causeof poor seating of the glenoid com-ponent in their series. Additionally,extensive removal of glenoid bonemay jeopardize component stability,leaving inadequate bone stock tosupport the implant. Removal ofbone also effectively medializes theglenohumeral joint line, thereby al-tering both glenohumeral biome-chanics and soft-tissue tensioning.Although humeral lateralization maybe improved by increasing the size ofthe humeral head, the effect of in-creased humeral component size isunknown.

Several studies have attempted toinvestigate limits to eccentric ream-ing for posterior glenoid erosion.Clavert et al18 eccentrically reamedfive cadaver shoulders to create gle-noid retroversion of ≥15° and im-planted a four-pegged glenoid com-ponent in each. Subsequent CT scansof the shoulders demonstrated peg

Illustration of the landmarks usedto assess glenoid version on CT. Aline (ie, Friedman line [blue]) isdrawn perpendicular to the axisalong the glenoid surface to defineneutral version (yellow line). Theangle from either the posterior(retroversion) or anterior(anteversion) margins of theglenoid indicates the nativeversion. The black dashed line liesacross the face of the glenoid. Thered scapula line extends parallel tothe scapula body.

Figure 3



penetration in all specimens which,in theory, limits the cement mantlearound each peg and may be a factorin glenoid component loosening. Ul-timately, the authors concluded thatretroversion ≥15° cannot be cor-rected with eccentric reaming. In an-other cadaver study, Gillespie et al19

simulated posterior glenoid wear in5° increments, then eccentricallyreamed to neutral and implantedpegged glenoid components. In fourof the eight specimens, placement ofa glenoid prosthesis was not possibleafter correction of 15° retroversionsecondary to inadequate bone stockand peg penetration. A 20° defor-mity was not correctable in six speci-mens. These authors concluded thateccentric reaming to correct poste-rior wear >15° has only a 50%chance of successful correction by ec-centric reaming and that instead,bone grafting should be consideredto address this defect.

Nowak et al20 used 3D models cre-ated from CT scans of patients withadvanced glenohumeral OA to simu-late asymmetric reaming and resur-facing in varying degrees of glenoidretroversion. They used an in-linethree-peg glenoid component as theresurfacing implant. Correction ofglenoid retroversion <12° did not re-sult in vault penetration. However,all glenoids with retroversion >18°demonstrated component peg pene-tration. Ultimately, results from thisstudy demonstrate that advancingdegrees of retroversion beyond 12°,and all of those over 18°, may not beamenable to correction by eccentricreaming.

Clinical results of TSA followingasymmetric reaming are limited.Habermeyer et al21 prospectivelystudied a cohort of patients undergo-ing TSA to address posterior glenoidwear. In all cases, the humeral headwas maintained in a recentered posi-

tion following surgical correction ofglenoid alignment in the transverseplane and soft-tissue balancing. Ger-ber et al22 reported that eccentricreaming resulted in correction ofposterior humeral subluxation in 21of 23 patients (91%). No correlationwas found between the ability to re-center the humeral head and the de-gree of preoperative glenoid versionor correction.

Several cadaver and clinical investi-gations have demonstrated the effec-tiveness and safety of computer navi-gation in improving measurement ofversion intraoperatively.23-25 Kircheret al24 reported improved versioncorrection using computer naviga-tion in a prospective, randomizedclinical trial. Version correction from15.4° to 3.7° was achieved with nav-igation, whereas correction withoutnavigation resulted in improvementfrom 14.4° to only 10.9°. Nofollow-up outcome data were ob-

Illustrations demonstrating characterization of the glenoid surface with eccentric wear using three new reference lines:Walch type B2 glenoid with posterior erosion (A), paleoglenoid (B), intermediate glenoid (C), and neoglenoid (D). Theinset images indicate that the cross section in each panel is at the midportion of the glenoid. (Adapted with permissionfrom Rouleau DM, Kidder JF, Pons-Villanueva J, Dynamidis S, Defranco M, Walch G: Glenoid version: How tomeasure it? Validity of different methods in two-dimensional computed tomography scans. J Shoulder Elbow Surg2010;19[8]:1230-1237.)

Figure 4



tained; however, the use of naviga-tion appears to improve glenoid po-sitioning and provides immediate,objective measurements of glenoidversion.

Eccentric reaming to correct ver-sion is a common and useful surgicaloption. However, there are limita-tions to the degree of version thatmay be appropriately corrected.

Posterior Bone Graft

Bone grafting provides a biologic so-lution in cases of substantial boneloss that prevents adequate versioncorrection or secure seating of a gle-noid component. Indications for

bone grafting include uneven wearthat cannot be accommodated bysmall changes in glenoid or humeralcomponent version, insufficient bonevolume to support the glenoid com-ponent, >15° of retroversion, andpotential penetration of the glenoidvault after version corrections.26-28

Advantages of bone grafting in thesetting of posterior bone deficienciesinclude preservation of anterior gle-noid bone stock and maintenance ofa more normal joint line that avoidsaltered joint kinematics secondary toshortening of the glenoid vault. Ad-ditionally, theoretically, bone graft-ing provides a permanent restorativesolution to glenoid bone loss. Disad-

vantages include graft dissolution,nonunion, fixation failure, and shiftleading to settling. Additionally,bone grafting is technically difficultand not reproducible as a result ofhigh variability with graft contour-ing.

Multiple grafting techniques havebeen described, with varying results.Three retrospective reviews in the lit-erature have reported the results ofbone grafting for eccentric glenoidwear, with incidence rates rangingfrom 3.3% to 16% of primaryshoulder arthroplasties.26-28 Neer andMorrison26 reported excellent resultsin 16 patients and satisfactory results(or attainment of desired limitedgoals) in 3 patients, and no revisionsurgeries. No glenoid loosening ormigration had occurred at a mini-mum follow-up of 2 years (average,4.4 years). Steinmann and Cofield27

reported less favorable results intheir series of 28 patients who under-went bone grafting for eccentricwear; however, this study includedpatients with instability. Fifteen pa-tients (54%) demonstrated some de-gree of radiographic lucency, andthree glenoids were radiographicallyloose at an average follow-up of 5.3years (range, 2 to 11 years). Despitethese findings, patient satisfactionwas similar to that reported by Neerand Morrison.26 In the most recentseries, Hill and Norris28 reported on17 shoulders that required bonegrafting secondary to anterior orposterior instability. In this challeng-ing patient population, there werefive glenoid failures requiring revi-sion as a result of instability (two pa-tients), one recurrent rotator cufftear, one improper placement of gle-noid component, and one glenoidfailure. These complications oc-curred within 2 to 91 months of theinitial surgery. Nine of 17 shoulderswere stable after bone grafting(53%), with a similar distributionfor functional satisfaction.

Illustrations of eccentric reaming to create a neutral articulation between thebone and glenoid prosthesis. A reamer in the neutral position is used to reamdown the high side (A) to create a perpendicular articulating surface that canaccept the glenoid implant (B). Although version can be corrected, theglenoid is medialized, and the width of the remaining glenoid bone becomesnarrower following the removal of anterior bone.

Figure 5



At our institution, bone loss >10 to15 mm as measured on axial CTscans is an indication for bone graft-ing. Ideally, the native osteotomizedhumeral head can be used as a struc-tural graft. There are no current pub-lished investigations regarding thistechnique; however, we have foundutilization of the native humeralhead to be very useful as it is typi-cally structurally sound and essen-tially precontured to match the gle-noid defect. The center of the glenoidcan be identified with the help ofspecialized cannulated sizer disks.Using these disks, a centralizedguide-wire is drilled perpendicular tothe neutral glenoid axis, which al-lows for version correction throughlimited reaming of the high side ofthe glenoid. The deficient side is thenlightly prepared with a burr to ex-pose a bleeding surface to receive thebone graft. The graft is contoured tofit the defect and placed with the ar-ticular side (ie, subchondral bone)facing the glenoid. The curvaturestypically closely match because thenative humeral head is accountablefor creating the defect. The graft is

temporarily fixed with small Stein-mann pins, which are replaced withcountersunk 3.5-mm screws posi-tioned to avoid glenoid implant pegs.The graft contour is then further re-fined with a burr, and the holes aredrilled for glenoid implantation.Trial glenoid implantation is essen-tial to ensure secure seating and fit ofthe glenoid prosthesis to the bone.

Augmented GlenoidComponent

New prosthetic solutions to glenoidbone loss have been driven by limita-tions in other options, such as dem-onstrated lack of durability and earlyglenoid failure in patients witheccentric wear.29,30 Although aug-mented components with a fixedpolyethylene buildup theoreticallymay ensure more reliable restorationof the joint line, the mechanicalproperties of polyethylene in this set-ting are unknown.

Although the concept of glenoidcomponent augmentation is not new,there is a paucity of data on its effi-

cacy. Neer et al31 initially presentedan augmented glenoid componentconsisting of a sloped posteriorbuildup. However, description of thisdevice was limited, and we are un-aware of any results on its use. Riceet al30 reported on their results usinga Cofield 2 keeled all-polyethyleneaugmented glenoid (Smith &Nephew, Memphis, TN), which wasimplanted in 14 shoulders with OAand associated posterior glenoid de-ficiency. This augmented componentprovided version correction of ap-proximately 4°. Despite satisfactorymidterm pain relief and functionaloutcome, use of this component wasdiscontinued as a result of persistentinstability.

Other augmented glenoid compo-nents have been recently introduced,such as the Global Steptech APG(DePuy, Warsaw, IN) and the Poste-rior Augment Glenoid (Exactech,Gainesville, FL). These offer an alter-native to asymmetric reaming andbone grafting (Figure 6). The long-term clinical performance of theseaugmented components has not beenevaluated.

Dysplastic Glenoid

Walch et al9 defined type C glenoidmorphology as glenoid retroversionof >25° regardless of the degree oferosion. This is most commonly as-sociated with congenital or dysplas-tic development. Normal glenoidfossa development occurs from prox-imal and distal ossification centers.32

Incomplete ossification of one orboth of these centers may cause un-derdevelopment of the posterior andinferior cartilaginous glenoid andneck of the scapula.33 Although gle-noid dysplasia is thought to be rare,reports indicate that it may be morecommon than previously specu-lated.9,34 Edelson34 examined 1,150scapular bone specimens from sev-

A, Preoperative axillary radiograph of a type B2 glenoid demonstratingapproximately 7 mm of posterior bone erosion. B, Postoperative axillaryradiograph following implantation of the Global Steptech APG augmentedglenoid component (DePuy, Warsaw, IN) and 7 mm of posterior buildup.

Figure 6



eral museum collections representingseveral different ethnic populations.He found localized hypoplasia of theposteroinferior glenoid in 20% to35% of specimens. Even so, a directlink between glenoid dysplasia andsecondary development of glenohu-meral OA has not been established.Edwards et al35 reported that only3.5% of patients with primary OAundergoing TSA were found to haveglenoid dysplasia.

Although excessive glenoid retro-version is characteristic of the dys-plastic shoulder, the humerus andsurrounding soft tissues appear toadapt to the glenoid morphology,thereby allowing the humeral headto remain centered in the retrovertedsocket. That is, even though the cen-ter of the humeral head lies posteriorto the scapular plane, it is containedwithin the anterior and posteriorconfines of the glenoid surface (Fig-ure 7). This important feature distin-guishes the hypoplastic glenoid fromthe biconcave (type B2) glenoid,which is associated with extensiveglenoid bone erosion and posteriorhumeral head subluxation with re-spect to the glenoid surface. Poste-rior glenoid erosion was minimal inone series of 15 patients with OAand dysplasia.35 Additionally, thesepatients had developed posteriorsoft-tissue hyperplasia that seeminglyprevented posterior subluxation.During glenoid preparation, the in-vestigators reamed to the native gle-noid (ie, no eccentric reaming) andmade no attempt to correct versionor augment posterior soft tissue. Atour institution, the posterior capsuleis also preserved in such cases as acheckrein to posterior displacementof the humeral head.

Although there are limited reportson surgical treatment in symptomaticpatients with dysplastic glenoids,shoulder arthroplasty has beenshown to be a viable option.35,36 Ed-wards et al35 reported significant im-

provement in outcome following ar-throplasty, including increased painrelief, motion, and function. In casesof severe dysplasia, the amount ofbone available for fixation may beinadequate for standard fixation op-tions. In these patients, the use of aninset bone-sparing glenoid compo-nent with a single, short peg may behelpful to avoid cortical penetra-tion.29 Complete correction of ver-sion in dysplastic glenoids can resultin substantial loss of internal rota-tion as a result of excessive tension-ing of posterior tissues. Unlike thetype B2 glenoid, the dysplastic gle-noid is associated with minimal pos-terior subluxation of the humerusand, therefore, the posterior tissuesare not excessively lax. Thus, aggres-sive version correction can place ten-sion on the posterior soft tissues andlimit the ability of the humerus to ro-tate internally. However, partial cor-rection may be attempted to restorenative retroversion if the humeralhead has eroded into the posteriorglenoid. In sedentary persons and el-derly persons (aged >70 years),

placement of reverse TSA, which is amore constrained device, may beconsidered to stabilize the glenohu-meral joint.

In cases in which bone erosion orversion is too significant to allowplacement of a glenoid component,replacement of the humeral headwithout glenoid resurfacing has beenshown to result in acceptable out-comes, even in young patients.37 Thecriteria used by Edwards et al35 forglenoid resurfacing was ≥15 mm ofglenoid bone depth on axial CT.These investigators found that pa-tients who underwent hemiarthro-plasty still had significant improve-ments in pain scores and functionalmeasures. A recent investigation byBonnevialle et al37 reported markedimprovement in pain scores, func-tion, and outcome measures at aminimum 2-year follow-up in ninepatients treated with hemiarthro-plasty for dysplasia. The authorsconcluded that hemiarthroplasty is areliable management option for thispatient population. Glenohumeralarthritis secondary to glenoid dyspla-

Axial CT scan (A) and sagittal three-dimensional CT reconstruction (B) of adysplastic glenoid. Although this glenoid is in >35° of retroversion, it remainscontained within the anterior and posterior confines of the glenoid surface.This finding distinguishes the morphology of the dysplastic glenoid from thetype B2 glenoid, in which the humeral head lies subluxated posteriorly andthe glenoid has a biconcave appearance.

Figure 7



sia appears to be relatively uncom-mon, but it may be effectively man-aged with TSA or hemiarthroplastywith limited correction of the naturalversion of the glenoid.

Summary

Advanced glenohumeral OA is asso-ciated with increased glenoid retro-version, posterior erosion, and gle-noid bone loss. Surgical resurfacingof the glenoid requires correction ofthese anatomic alterations to allowplacement of the implant in near-neutral version with adequate bonystructural support. This is done in aneffort to avoid early failure of the re-placement. Selection of surgical tech-nique depends on the severity of de-formity and the degree of bone loss.Typically, minor changes in versionand limited bone loss can be ade-quately corrected with eccentricreaming of the glenoid to neutral ornear-neutral version. However, ex-tensive glenoid bone loss may requireaugmentation with either bone graftor specialized glenoid implants to re-store version and support glenoidcomponent implantation. Extensivebone loss may make glenoid resur-facing impossible.

Glenoid bone loss is a challengingproblem that is commonly encoun-tered with the osteoarthritic glenoid.Appropriate assessment and correc-tion are critical for long-term out-comes following TSA. Further re-search is necessary to determine themost effective approach to glenoidmanagement in these difficult cases.

References

Evidence-based Medicine: Levels ofevidence are listed in the table ofcontents. In this article, references 2,8, 9, 17, and 24 are level II studies.References 1, 4, 5, 12, 13, 21, 23, 28,

29, and 34 are level III studies.References 3, 22, 26, 27, 30, 32, 33,and 35-37 are level IV studies.Reference 31 is level V expertopinion.

References printed in bold type indicatethose published within the past 5 years.

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Glenoid Bone Loss in Primary Total Shoulder Arthroplasty ... · Glenoid bone loss has been shown to...

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