A mobile separation of the superior and inferior hemipelvis: diagnose the biology, then stabilise the ring
- Pelvic discontinuity is a ring instability problem. A hemispherical shell fixed to one mobile hemipelvic segment is not enough.
- Differentiate an acute intraoperative fracture from chronic fibrous discontinuity; the reduction, bone preparation and fixation goals differ.
- The sciatic nerve, superior gluteal vessels, obturator structures, iliac vessels and pelvic viscera are at risk during column preparation and screw placement.
- The implant must restore a stable hip centre without excessive medialisation or lengthening, and the reconstruction must tolerate a protected loading period.
- Infection is a frequent co-pathology. A draining sinus or positive deep cultures changes the operation to a staged salvage pathway.
- “The key examination finding is motion or pain through the pelvic ring, often with a migrated or unstable acetabular component.
- “A chronic discontinuity may be fibrous and difficult to see on one radiograph; compare serial images and use CT, sometimes with dynamic or intraoperative assessment.
- “Cup-cage constructs use a porous shell for host-bone fixation and a cage to bridge the discontinuity and support a cemented liner.
- “Custom triflange and distraction are alternatives when a standard cup-cage cannot obtain reliable three-dimensional fixation.
Definition and Mechanisms
What it is. Pelvic discontinuity is a complete separation between the superior and inferior acetabular columns, producing a mobile pelvic ring. It may be acute, created during component removal or reaming, or chronic, persisting as a fibrous nonunion after severe bone loss, fracture or repeated revision. The discontinuity can be transverse, oblique or irregular and may coexist with anterior or posterior column deficiency.
How often, and in whom. Berry found 31 discontinuities in 3,505 acetabular revisions, 0.9 per cent. Female sex and rheumatoid arthritis significantly increased the risk, and 28 of the 31 hips were in women. In a woman with rheumatoid arthritis and a migrated cup, look for the radiographic signs deliberately rather than incidentally.
How it arises. The recognised routes are:
- progressive osteolysis and medial migration of a loose acetabular component
- fracture through a thin superior and inferior column during revision extraction or reaming
- old acetabular fracture or pelvic trauma
- repeated revision, cage failure and structural allograft resorption
- infection with bone destruction and nonunion
- radiation, metabolic bone disease or severe osteopenia
The mechanical problem. It has two parts: the acetabular bone cannot support a normal hemispherical shell, and the pelvic segments can move relative to one another. A reconstruction must therefore provide immediate stability while allowing biological incorporation or long-term load transfer.
Anatomy and Structures at Risk
The columns. The acetabulum is the junction of the anterior column, posterior column, superior dome, pubis and ischium. Discontinuity may leave the columns thin and displaced, with the pelvic organs closer to the reconstructed cup than expected.
Structures at risk by region. Each part of the acetabulum has its own neighbours:
- Anterior column and pubis: close to the obturator nerve and vessels, the bladder, and the external iliac or femoral vessels depending on the trajectory.
- Posterior column and ischium: close to the sciatic notch and nerve. The posterior column provides an important bridge for cup-cage or custom fixation.
- Ilium: supports superior flange or screw fixation, but its inner table borders iliacus and the pelvic viscera, and the superior gluteal bundle exits through the greater sciatic notch.
- Acetabular floor: medial defects can expose obturator internus, the pelvic muscles, vessels and viscera, and a medialised cup can impinge on intrapelvic structures.
- Femoral nerve and vessels: anterior retractors and screws near the superior pubic ramus or iliopectineal line require controlled exposure.
- Sciatic nerve: at risk from posterior retractors, a migrated cup, screw breach, excessive leg lengthening and postoperative haematoma.
The safe corridor is patient-specific. Prior migration, pelvic fracture, vascular surgery and radiation increase the risk of iliac vessel or visceral injury. Vascular or general-surgical assistance should be planned rather than summoned after bleeding begins.
Classification and Decision Framework
A practical classification describes chronicity, mobility, bone loss and biology. Two systems are in use and they answer different questions: the defect classification (Paprosky) says what bone is left, while the discontinuity pattern says what the ring is doing.
- Features
- Fresh fracture during extraction or reaming; segments usually reducible
- Reconstruction implication
- Reduce immediately, protect the columns and stabilise with a cage, plates, cup-cage or other bridge
- Features
- Long-standing separation with little gross movement and residual host bone
- Reconstruction implication
- A porous shell plus cage, custom component or distraction can obtain fixation if both segments are captured
- Features
- Painful motion, migrated component and extensive column loss
- Reconstruction implication
- Requires a construct that stabilises the entire pelvic ring; custom triflange or cup-cage may be selected by CT
- Features
- Sinus, purulence, positive cultures, abscess or non-viable bone
- Reconstruction implication
- Stage debridement and dead-space management; do not place definitive reconstruction into active infection
Chronicity is the load-bearing distinction. An acute intraoperative discontinuity is a fracture in living bone with healing potential: reduce it, stabilise it and it can unite. A chronic discontinuity is an established fibrous nonunion whose surfaces will not heal without being freshened, grafted and compressed or distracted. That is why the constructs differ with chronicity instead of merely scaling with severity.
Reconstruction Options
What every construct must do. The superior and inferior hemipelvis must be stabilised as a unit. A standard shell fixed to one mobile segment will fail however well it is screwed, and a cup that moves with one segment will loosen even if its inclination looks correct. Something in the construct must also integrate biologically with living bone: the porous shell in a cup-cage, the press-fit shell in distraction, the flanges in a triflange.
Spanning is not healing. A cage that bridges the discontinuity without achieving union leaves micromotion, and micromotion causes late fatigue failure. Abolghasemian found union across the discontinuity in every successful cup-cage but in only 3 of the successful cages, which is why the cup-cage displaced the ilioischial cage alone: 87.2% against 49.9% survivorship at seven years, p = 0.009.
- Strength
- Porous shell obtains host-bone fixation while cage bridges columns and supports a cemented liner
- Limitation
- Cage fatigue, dislocation, infection and dependence on biological cup fixation
- Strength
- Patient-specific iliac, ischial and pubic flanges can capture both hemipelvic segments
- Limitation
- Design lead time, CT dependence, screw and visceral risk, high complication burden
- Strength
- Uses controlled distraction to tension the discontinuity and obtain a press-fit shell in remaining bone
- Limitation
- Requires suitable bone, careful sizing and an experienced team; not appropriate for every mobile defect
- Strength
- Directly stabilises columns and can restore bone in selected acute defects
- Limitation
- Graft resorption, nonunion, hardware failure and difficult future revision
- Strength
- Removes uncontrolled infection or non-viable tissue when reconstruction is unsafe
- Limitation
- Loss of hip stability or limb, high rehabilitation burden and major functional consequences
Price is not the obstacle to a triflange. Taunton priced a custom triflange at 12,500 US dollars against 11,250 for a trabecular metal cup-cage, which removes the usual argument against a custom implant. The figure is an implant list price at one time in one country and excludes theatre time and the cost of reoperations, but it means the decision should turn on the bone pattern and the lead time.
What the published survivorship is. The table above says which construct does what; these are the numbers behind the choice. They come from separate uncontrolled series and are not a head-to-head comparison, since no randomised or matched study exists, so read them as orders of magnitude and not as a ranking.
- Series
- Abolghasemian, 19 hips
- Result
- 49.9% at 7 years; 68% failed, and the construct is effectively abandoned
- Series
- Abolghasemian, 26 hips
- Result
- 87.2% at 7 years
- Series
- Sculco, 57 patients (60% discontinuity)
- Result
- 89% free of re-revision or reoperation, mean 5 years
- Series
- Sporer, 20 hips
- Result
- 1 of 20 re-revised for aseptic loosening, mean 4.5 years
- Series
- Taunton, 57 patients
- Result
- 98% free of revision for aseptic loosening, but only 65% free of revision for any reason
- Series
- De Martino, 579 implants
- Result
- 82.7% all-cause survivorship, 29% complication rate: dislocation 11%, infection 6.2%, nerve injury 3.8%, aseptic loosening only 1.7%
Read the triflange rows together. Fixation to bone is close to solved: aseptic loosening runs at 1.7 to 2 per cent. What remains, the third of patients who are reoperated, is instability and infection. The construct decision is therefore not the whole operation. Plan the bearing, the offset and head size, the abductor mechanism and the infection strategy with the same care as the fixation, because that is where these reconstructions now fail.
The bearing. Choose a bearing that matches stability and soft-tissue deficiency. Dual mobility may reduce instability risk, while a constrained liner increases forces on the reconstruction and should be used selectively. No liner can rescue a cup that is mechanically loose.
History and Examination
History. Ask about the primary arthroplasty, every revision and cage or augment, prior fracture, bone graft, infection, sinus, radiation, pelvic or abdominal surgery, vascular disease and the timing of pain or leg-length change. Start-up pain, a clunk or a sense that the pelvis shifts during transfers suggests instability. Record mobility, walking aids, sitting tolerance, shoe lifts and the patient's ability to tolerate protected weight bearing.
Look and walk. Record shortening, Trendelenburg gait, trunk shift, scars, flaps, sinus and pelvic asymmetry. Observe transfers and a short walk if safe; a large pelvic movement may be felt as the patient turns.
Feel. Palpate the greater trochanter, iliac crest and pubic region for tenderness. Assess the soft-tissue envelope and map any sinus. Avoid forceful manipulation when a fracture or vascular threat is possible.
Move. Test hip flexion, abduction, rotation and pain with gentle loading, and compare the opposite hip and knee. Record abductor power and pre-existing contractures.
Neurological and vascular. Document sciatic nerve function, femoral nerve function when anterior structures are involved, and distal pulses. A preoperative deficit changes counselling and the urgency of screw or implant planning.
Imaging and Diagnosis
Plain radiographs. Obtain an AP pelvis, Judet views when useful, a cross-table lateral and serial comparison; a long-leg standing film may be needed for length and mechanical axis. The AP must be a true AP. Two of Berry's three signs are asymmetries, so a rotated film destroys them, and this is the commonest reason the diagnosis is missed until the hip is open.
Berry's three signs. On a true AP pelvis:
- A visible fracture line through both the anterior and posterior columns. Its absence does not exclude a chronic fibrous discontinuity.
- Medial translation of the inferior hemipelvis, seen as a break in Kohler's line, the sign most often visible before the fracture line is.
- Rotation of the inferior hemipelvis, seen as asymmetry of the obturator rings. Compare the two rings against each other, not against a remembered normal.
Look also for:
- migration or rotation of the cup or cage
- change in the teardrop or hip centre
- progressive radiolucency, broken screws, cage hooks or protrusio
- discontinuity of the ilioischial and iliopectineal lines
- leg-length change and femoral component position
Judet views may show column defects, but severe deformity and overlapping hardware can obscure the diagnosis.
CT. Thin-slice CT with metal artefact reduction maps the discontinuity, column thickness, bone loss, implant position, cement, screw corridors and intrapelvic structures. Read axial slices first, then coronal and sagittal reconstructions. A 3D model helps communication but can hide a thin cortex or an unrecognised vessel relationship.
Dynamic or intraoperative assessment. A chronic discontinuity may be fibrous, with subtle radiographic motion. Compare serial radiographs, examine for component movement and assess stability after exposure. Intraoperative movement under controlled conditions is useful only after infection and vascular risk have been considered, because forceful manipulation can create a fracture or bleeding.
Infection. Use a composite periprosthetic infection work-up. A sinus, purulence or concordant deep cultures require staged treatment, and definitive cup-cage or custom metal should not be used to bury uncontrolled infection.
Vascular assessment. Obtain CT angiography, and involve vascular surgery before extraction, when the cup has migrated medial to the iliopectineal line, the patient has had prior pelvic surgery, or CT shows a component, screw or defect close to a vessel.
Operative Technique: PIPADRAW
Pelvic discontinuity reconstruction sequence
- Use a lateral or supine position according to the approach, secure the pelvis and leave the full limb free for reduction, length assessment and fluoroscopy.
- Prep from the costal margin to the foot when an extensile approach, vascular exposure or flap may be needed.
- Place a urinary catheter and coordinate with anaesthesia for blood loss, cell salvage, neuromonitoring and vascular control.
- Obtain a baseline AP pelvis and confirm that fluoroscopy can image the iliac, posterior column, ischial and pubic regions.
- Have the chosen implant, cage, plates, screws, trial liners, extraction tools, graft and a backup construct in theatre.
- Review CT angiography or vascular advice before incision when intrapelvic hardware is present.
- Administer antibiotics after cultures where appropriate and use the agreed therapeutic plan for established infection.
- Confirm whether this is acute or chronic, stable or mobile, and whether the plan is definitive or staged.
- Prepare blood products, thrombosis strategy and a soft-tissue coverage plan.
- Choose the safest previous approach or an extensile approach that preserves skin bridges. Excise a sinus tract en bloc.
- Expose the acetabulum and columns without blind intrapelvic retraction. Identify the sciatic nerve when the posterior column is scarred.
- Coordinate with vascular or general surgery before manipulating a migrated cup near a vessel or organ.
- Remove the liner, shell, cage, cement and loose screws with controlled extraction. Do not pull a migrated component blindly.
- Obtain multiple deep samples and histology before antibiotics when safe. Debride infected membrane and non-viable bone while preserving viable column attachments.
- Define the superior and inferior hemipelvic segments, the discontinuity gap and the remaining fixation surfaces.
- Freshen a chronic nonunion only to bleeding viable bone and correct gross displacement. Avoid removing the last thin column that will support the construct.
- Trial the cup-cage, custom component or distraction device against the planned bone surfaces. Ensure the component can capture both segments.
- Prepare graft or porous contact surfaces according to the implant system and keep the pelvic cavity protected.
- Reduce the hemipelvic segments around the trial construct and check the hip centre, inclination, version, offset and leg length.
- Balance restoration of the hip centre and offset against sciatic nerve tension. In a multiply revised limb a planned modest shortening may be safer than stretching a scarred nerve.
- Check the femoral component, abductor tension and stability through a controlled range before final fixation.
- Use controlled retraction and never place a screw freehand into a thin column or an unexamined pelvic wall.
- Drill with stops or navigation and check screw length with orthogonal imaging. Keep trajectories away from the sciatic notch, obturator canal, iliac vessels and bladder.
- If a vessel or organ is exposed or injured, stop reconstruction and obtain specialist control before proceeding.
- For a cup-cage, obtain host-bone fixation with the porous shell, seat the cage across the discontinuity and cement the liner after the cage is stable.
- For custom triflange, seat the iliac, ischial and pubic flanges, drill planned corridors and tighten in a sequence that captures both segments.
- For distraction or plates, apply the validated compression or distraction method and add graft where a biological bridge is required.
- Obtain AP pelvis and oblique or cross-table images of the columns and all critical screws.
- Confirm that the hip centre is not excessively medial or high, the cage or flanges are seated, the liner is oriented, the femoral component is stable and no hardware penetrates the pelvis.
- If fixation is inadequate, revise before closure; a postoperative CT cannot repair an avoidable breach.
- Irrigate, obtain haemostasis and close with durable muscle and fascial coverage. Involve plastic surgery early when the envelope is marginal.
- Apply approach- and bearing-specific precautions and toe-touch or partial weight bearing until radiographic and clinical review supports progression.
- Continue infection treatment, thrombosis prevention, neurovascular checks and early transfer training.
Complications and Salvage
- Clues
- Sinus, drainage, fever, positive cultures or loosening
- Immediate response
- Cultures, imaging and infection-team review
- Definitive principle
- Stage debridement and dead-space management; repeat reconstruction only after a realistic infection plan
- Clues
- Early instability or recurrent reduction
- Immediate response
- Reduce, document sciatic function and image
- Definitive principle
- Correct cup orientation, hip centre, offset, liner and soft-tissue cause
- Clues
- New foot drop, sensory loss or severe postoperative pain
- Immediate response
- Check dressings, image screws and assess lengthening
- Definitive principle
- Remove a causative screw or revise compression/length urgently with specialist support
- Clues
- Bleeding, pulse change, groin pain, haematuria or bowel symptoms
- Immediate response
- Resuscitate and obtain CT angiography or urgent operative control
- Definitive principle
- Do not remove hardware blindly; involve vascular or general surgery
- Clues
- Persistent pain, pelvic movement or progressive component change
- Immediate response
- Exclude infection and obtain CT
- Definitive principle
- Revise with stable fixation and biological graft only when expected function justifies the risk
- Clues
- Broken screws, loss of cup position or metal fatigue
- Immediate response
- Protect weight bearing and image the full reconstruction
- Definitive principle
- Treat pelvic stability, infection and bearing together; isolated liner exchange is rarely enough
Postoperative Care and Surveillance
Protected loading. Protective weight bearing is commonly used for several weeks and is prolonged when the discontinuity is mobile, bone quality is poor, a structural graft is present or fixation is marginal. Advance loading only after serial radiographs show stable cup position, cage or flange fixation and progressive incorporation.
Review. At each visit assess the wound, fever, drainage, sciatic function, limb length, hip stability, groin pain and the ability to transfer. Obtain an AP pelvis and appropriate oblique or cross-table views. CT is useful for uncertain union, component migration, screw breach or unexplained pain.
Three independent series report the same pattern: a construct that moves radiographically in the first months, then stabilises and succeeds. In Abolghasemian's series 3 cup-cage hips migrated early and all stabilised with a successful outcome. In Sculco's, 4 migrated and all but one stabilised before the 2-year mark. In Sporer's, 4 distraction constructs migrated early and remained asymptomatic and radiographically stable.
A construct that has settled slightly on the 6-week or 3-month film is therefore watched with serial radiographs, not re-revised; re-revising an early migration is a real and avoidable harm. Abolghasemian attaches the condition: this holds provided the bone graft at the discontinuity site has not been disrupted.
What matters is progressive migration on sequential films, so book the interval films rather than waiting for symptoms. Measure against the immediate post-operative radiograph, not against memory or the 6-week film alone, and remember that a single displaced measurement is not evidence of failure. Exclude infection before attributing movement to settling, because infection and aseptic loosening both present as a construct that moves.
Guidelines, Registries & Global Practice
Global evidence. Pelvic discontinuity is rare and evidence is mainly from small series, systematic reviews and expert centres. No single construct is universally superior. Cup-cage, custom triflange and distraction can all provide durable salvage in selected patients, but complication and reoperation rates remain substantial.
Consensus principles.
- Define chronicity, mobility, bone loss and infection before choosing a construct.
- Stabilise both hemipelvic segments; a component fixed to one mobile fragment is mechanically inadequate.
- Use thin-slice CT and, when indicated, CT angiography to map bone and intrapelvic structures.
- Restore hip centre, length, offset and version without excessive sciatic nerve tension.
- Obtain multiple deep cultures and stage active infection rather than implanting definitive metal through a sinus.
- Protect weight bearing until the reconstruction shows stable incorporation.
Registries. National arthroplasty registries contain valuable data on revision burden and acetabular failure but rarely identify pelvic discontinuity, chronicity or specific reconstruction in a sufficiently detailed category. Centres should record the discontinuity pattern, construct, bearing, infection status, union, migration and reoperation.
Global practice. Custom manufacturing and navigation are available in some centres; cup-cage, cage-and-plate or staged reconstruction may be more accessible elsewhere. The principle is not technology-specific: achieve a stable ring with viable bone and protect the organs, nerves and soft tissues.
MCQ Practice Points
Q: What is pelvic discontinuity, and how common is it?
A: A complete separation between the superior and inferior acetabular columns producing a mobile pelvic ring. It may be acute — created during revision, usually while removing a well-fixed component — or chronic, a fibrous or non-united defect after osteolysis, fracture, infection or cage failure. Berry found it in 31 of 3,505 acetabular revisions, 0.9 per cent, so a busy revision surgeon meets it rarely. Two risk factors reached significance in that series and are worth quoting: female sex (28 of 31 hips, p less than 0.001) and rheumatoid arthritis (p = 0.003).
Q: What do you look for on the plain AP pelvis?
A: Berry's three signs, on a true AP: (1) a visible fracture line through both anterior and posterior columns; (2) medial translation of the inferior hemipelvis, seen as a break in Kohler's line; and (3) rotation of the inferior hemipelvis, seen as asymmetry of the obturator rings. Two of the three are asymmetries, which is why the film must be a true AP and why the diagnosis is missed on a rotated one — and being missed preoperatively is how an elective revision becomes an unplanned discontinuity reconstruction.
Q: What must any construct achieve?
A: It must capture and stabilise both hemipelvic segments. A standard shell fixed to one mobile segment will fail. The corollary is the reason cages alone were abandoned: a construct that merely bridges the discontinuity without achieving union across it leaves persistent micromotion and fails by late fatigue. Abolghasemian showed union of the discontinuity in every successful cup-cage but in only 3 of the successful cages, with seven-year survivorship 87.2 per cent against 49.9 per cent (p = 0.009).
Q: Which construct, and on what grounds?
A: There is no head-to-head comparison, so the choice is made on the bone pattern rather than on published superiority. A cup-cage combines a porous shell for host-bone fixation with an ilioischial cage bridging the discontinuity, supporting a cemented liner — the best-evidenced option, and available as a half cup-cage decided intraoperatively on remaining host bone. Distraction suits a pattern with enough superior and inferior host bone to tension against, and works by eliminating micromotion rather than bridging it. A custom triflange captures both segments when little host bone remains, at the price of manufacturing lead time — and note the cost objection is unfounded, Taunton found a triflange at 12,500 US dollars against 11,250 for a cup-cage.
Q: A triflange series reports 98 per cent free of revision for aseptic loosening. What is the catch?
A: That figure and the honest one sit in the same results paragraph. In Taunton's 57 patients, 98 per cent were free of revision for aseptic loosening but only 65 per cent were free of revision for any reason — and only 49 per cent were free of revision, free of migration and had a healed discontinuity. De Martino's review of 579 implants shows why: aseptic loosening was 1.7 per cent but the overall complication rate was 29 per cent, with dislocation 11 per cent, infection 6.2 per cent and nerve injury 3.8 per cent. Fixation to bone is close to solved; the operation is not. Quote the all-cause figure.
Q: What causes the disasters in this operation?
A: Blind removal of hardware or screw placement near the intrapelvic vessels, viscera or sciatic nerve. Obtain CT angiography and specialist control before manipulating high-risk hardware. This is not theoretical: Sporer's series of 28 distractions records one vascular injury and one bowel injury alongside a single infection — the complications that maim rather than merely fail.
Exam Viva Scenarios
Practise clinical reasoning and management decisions out loud
“During removal of a loose acetabular component, the anterior and posterior columns fracture and the superior hemipelvis moves independently. There is no purulence and the preoperative CT showed reasonable bone stock. What do you do?”
“A 74-year-old has progressive pain, a migrated cup and a chronic mobile discontinuity. CT shows only a thin posterior column and a prior screw lies close to the external iliac vessels. How do you proceed?”
“A patient dislocates after cup-cage reconstruction for chronic pelvic discontinuity. The cup position is unchanged and CT shows no screw breach. What is your cause analysis?”
Diagnose
- Separate superior and inferior hemipelvic columns with mobility or fibrous nonunion
- Acute during revision versus chronic after osteolysis, fracture, infection or cage failure
- AP pelvis, Judet/serial views and thin-slice CT; CT angiography if hardware is near vessels
- Composite infection assessment and baseline sciatic/vascular examination
Choose
- Cup-cage: porous shell plus cage bridges columns and supports cemented liner
- Custom triflange: iliac, ischial and pubic flanges capture both segments
- Distraction: selected chronic discontinuity with suitable host bone
- Stage infection, non-viable bone or unsafe visceral/vascular anatomy
PIPADRAW
- Position, image, prepare vascular/infection plan and protect the full limb
- Approach through viable tissue, control migrated hardware and preserve columns
- Debride and culture; reduce discontinuity and restore hip centre without nerve over-lengthening
- Fix both hemipelvic segments, verify screws and liner, close and protect weight bearing
Complications
- Infection, dislocation, nerve palsy, vascular/visceral injury, nonunion and cage/flange failure
- Never remove a vessel-adjacent screw blindly
- A stable cup is not enough if the pelvic ring remains mobile
- Protect loading until serial imaging demonstrates incorporation
Evidence Base
Every card below was re-resolved against PubMed in August 2026 and the three it replaces were not sound. One named a paper that does not exist; one put a real paper in the wrong journal and added an author who is not on it; none carried a PMID or a single number. The reconstruction options are compared here with the survivorship figures that actually separate them.
Pelvic Discontinuity in Revision Total Hip Arthroplasty
- The paper that defined the entity: 31 discontinuities found among 3,505 acetabular revisions at one institution - an incidence of 0.9 PER CENT, which is why most revision surgeons see few
- STRIKING DEMOGRAPHIC SKEW: 28 of 31 hips were in WOMEN, and both female sex (p less than 0.001) and rheumatoid arthritis (p = 0.003) significantly increased risk. Mean age 61
- THE THREE RADIOGRAPHIC SIGNS, STILL THE ONES TO LOOK FOR, on a true AP: a visible fracture line through anterior and posterior columns; MEDIAL TRANSLATION of the inferior hemipelvis seen as a BREAK IN KOHLER'S LINE; and ROTATION of the inferior hemipelvis seen as ASYMMETRY OF THE OBTURATOR RINGS
- Outcome tracked the bone loss, not the technique: satisfactory in 3 of 3 type IVa hips, 10 of 19 type IVb, and 3 of 5 previously IRRADIATED type IVc
- 9 of 27 reconstructed hips needed a further operation - 4 aseptic loosening, 4 recurrent DISLOCATION, 1 deep infection - and a mechanically stable construct was achieved in only 17 of 24
The Challenge of Pelvic Discontinuity: Cup-Cage Reconstruction Does Better Than Conventional Cages in Mid-Term
- A direct comparison, which is rare in this field: 26 discontinuities treated by CUP-CAGE (mean follow-up 82 months) against 19 treated by ilioischial CAGE ALONE (mean follow-up 69 months)
- SEVEN-YEAR SURVIVORSHIP 87.2 PER CENT (95 per cent CI 71 to 103) FOR CUP-CAGE AGAINST 49.9 PER CENT (95 per cent CI 15 to 84) FOR CAGE ALONE, p = 0.009
- Failure from septic or aseptic loosening in 4 of 26 cup-cages (15 per cent) against 13 of 19 cages (68 PER CENT) - the cage-alone group failed more often than it succeeded
- Radiological union of the discontinuity occurred in ALL successful cup-cage cases but in only 3 of the successful cage cases
- EARLY MIGRATION IS NOT AUTOMATICALLY FAILURE: three cup-cage hips migrated early on radiographs, then stabilised and succeeded - provided the bone graft at the discontinuity was not disrupted
The Evolution of the Cup-Cage Technique for Major Acetabular Defects: Full and Half Cup-Cage Reconstruction
- 57 patients with Paprosky 2B to 3B defects, of whom 34 (60 PER CENT) had an associated pelvic discontinuity; 30 full cup-cage and 27 HALF cup-cage constructs, mean follow-up 5 years
- Harris hip score improved from 36 to 72 in both cohorts (p less than 0.05)
- Short-term survivorship free from re-revision or reoperation for any cause 89 PER CENT overall - 83 per cent for full and 96 per cent for half cup-cage
- AGAIN THE MIGRATION SIGNAL: early construct migration in 4 patients, which STABILISED before 2-year follow-up in all but one
- Non-progressive zone-3 radiolucencies in 2 of the full (7 per cent) and 6 of the half constructs (22 per cent), with only one re-revision for progressive migration and aseptic loosening
- The selection rule the authors state: full against half is decided INTRAOPERATIVELY on the extent and pattern of bone loss, the quality and location of host bone after preparation, and the presence of discontinuity
Acetabular Distraction: An Alternative for Severe Defects with Chronic Pelvic Discontinuity?
- The primary outcome series for the distraction technique: 28 chronic discontinuities reconstructed 2002 to 2006 with a porous tantalum elliptical component, alone or with modular tantalum augments
- 20 patients reached minimum 2-year follow-up (average 4.5 years, range 2 to 7); 3 died and 5 were lost
- ONLY 1 OF 20 required re-revision for aseptic loosening; 15 remained radiographically stable
- THE MIGRATION PATTERN AGAIN, IN A THIRD SERIES: 4 patients migrated early and then remained asymptomatic and radiographically stable
- Modified Merle d'Aubigne-Postel score improved by an average of 6.6 points (range 3.3 to 9.6)
- NO DISLOCATIONS in the series - but one infection, one VASCULAR injury and one BOWEL injury
- The rationale stated for the technique: plating with or without a cage can leave persistent micromotion across the discontinuity, causing late fatigue failure
Pelvic Discontinuity Treated with Custom Triflange Component: A Reliable Option
- MULTICENTRE, 57 patients with pelvic discontinuity treated with a custom triflange, minimum 24 months and average 65 months of follow-up (range 24 to 215)
- THE HEADLINE AND THE CAVEAT ARE IN THE SAME RESULTS PARAGRAPH AND ONLY THE FIRST GETS QUOTED: 56 of 57 (98 PER CENT) were free of revision for ASEPTIC LOOSENING - but only 37 (65 PER CENT) were free of revision FOR ANY REASON
- 54 (95 per cent) were free of revision of the triflange component itself for any reason, so most of the reoperations were for something other than the cup
- Only 28 (49 PER CENT) were free of any revision AND free of component migration AND had a healed discontinuity; 46 (81 per cent) had a stable component with a healed discontinuity
- Average Harris hip score 74.8 - a fair, not a good, result
- COST: custom triflange 12,500 US dollars against 11,250 for a trabecular metal cup-cage - the authors' point being that the custom implant is NOT the expensive option
Survivorship and Clinical Outcomes of Custom Triflange Acetabular Components in Revision Total Hip Arthroplasty: A Systematic Review
- PRISMA systematic review of 17 studies and 579 custom triflange acetabular components - the largest aggregate in the field
- All-cause revision-free survivorship 82.7 PER CENT
- OVERALL COMPLICATION RATE 29 PER CENT - the number that should be quoted alongside any triflange survivorship figure
- DISLOCATION 11 PER CENT and INFECTION 6.2 PER CENT were the commonest complications, while ASEPTIC LOOSENING WAS ONLY 1.7 PER CENT
- NERVE INJURY IN 3.8 PER CENT - roughly one patient in 26, which belongs in the consent form
- The authors' conclusion is deliberately double-edged: triflanges remain efficacious and have a high complication rate, and patients must be educated about reoperation risk
References
Every entry below was resolved against PubMed in August 2026. Five entries previously listed here could not be resolved as stated and have been corrected or replaced — see the note at the end.
- Berry DJ, Lewallen DG, Hanssen AD, Cabanela ME. Pelvic discontinuity in revision total hip arthroplasty. J Bone Joint Surg Am. 1999;81(12):1692-1702. PMID: 10608380. DOI: 10.2106/00004623-199912000-00006.
- Sporer SM, Bottros JJ, Hulst JB, Kancherla VK, Moric M, Paprosky WG. Acetabular distraction: an alternative for severe defects with chronic pelvic discontinuity? Clin Orthop Relat Res. 2012;470(11):3156-3163. PMID: 23001499. DOI: 10.1007/s11999-012-2514-1.
- Abolghasemian M, Tangsaraporn S, Drexler M, et al. The challenge of pelvic discontinuity: cup-cage reconstruction does better than conventional cages in mid-term. Bone Joint J. 2014;96-B(2):195-200. PMID: 24493184. DOI: 10.1302/0301-620X.96B2.31907.
- Sheth NP, Melnic CM, Paprosky WG. Acetabular distraction: an alternative for severe acetabular bone loss and chronic pelvic discontinuity. Bone Joint J. 2014;96-B(11 Suppl A):36-42. PMID: 25381406. DOI: 10.1302/0301-620X.96B11.34455.
- Sculco PK, Ledford CK, Hanssen AD, Abdel MP, Lewallen DG. The evolution of the cup-cage technique for major acetabular defects: full and half cup-cage reconstruction. J Bone Joint Surg Am. 2017;99(13):1104-1110. PMID: 28678123. DOI: 10.2106/JBJS.16.00821.
- Taunton MJ, Fehring TK, Edwards P, Bernasek T, Holt GE, Christie MJ. Pelvic discontinuity treated with custom triflange component: a reliable option. Clin Orthop Relat Res. 2012;470(2):428-434. PMID: 21997785. DOI: 10.1007/s11999-011-2126-1.
- Hansen E, Shearer D, Ries MD. Does a cemented cage improve revision THA for severe acetabular defects? Clin Orthop Relat Res. 2011;469(2):494-502. PMID: 20857251. DOI: 10.1007/s11999-010-1546-7.
- De Martino I, Strigelli V, Cacciola G, Gu A, Bostrom MP, Sculco PK. Survivorship and clinical outcomes of custom triflange acetabular components in revision total hip arthroplasty: a systematic review. J Arthroplasty. 2019;34(10):2511-2518. PMID: 31213338. DOI: 10.1016/j.arth.2019.05.032.
- Abdel MP, Trousdale RT, Berry DJ. Pelvic discontinuity associated with total hip arthroplasty: evaluation and management. J Am Acad Orthop Surg. 2017;25(5):330-338. PMID: 28350548. DOI: 10.5435/JAAOS-D-15-00260.
- Babis GC, Nikolaou VS. Pelvic discontinuity: a challenge to overcome. EFORT Open Rev. 2021;6(6):459-471. PMID: 34267936. DOI: 10.1302/2058-5241.6.210022.
Corrections made in August 2026. Two entries named papers that do not exist: "Martin CT, Callaghan JJ, Liu SS, et al. Distraction reconstruction for acetabular bone loss and pelvic discontinuity. J Bone Joint Surg Am. 2012;94:1943-1951" — no such paper; the real primary distraction series is Sporer 2012 in CORR, now reference 2. And "O'Shea K, Bale R, O'Brien S, et al. Management of pelvic discontinuity in revision total hip arthroplasty. EFORT Open Rev. 2023;8:208-218" — no such paper; the EFORT Open Rev review of this subject is Babis & Nikolaou 2021, now reference 10. Two attached real authors to the wrong title: Taunton's 2012 CORR paper is "Pelvic discontinuity treated with custom triflange component: a reliable option" at pages 428-434, not "The use of custom triflange acetabular components in the management of severe acetabular bone loss" at 484-492; and Hansen, Shearer & Ries wrote "Does a cemented cage improve revision THA for severe acetabular defects?" in CORR 2011;469:494-502, not "Does a custom triflange acetabular component provide enough stability for pelvic discontinuity?" in 2012;470:307-312. One could not be found at all — "De Martino I, D'Apolito R, Sculco PK, et al. 2D and 3D-printed custom triflange acetabular components... Hip Int. 2019;29:591-59" — and has been replaced by Abdel's JAAOS review, now reference 9.