Classify columns, walls, rim, medial migration and pelvic continuity before choosing the reconstruction
- The Paprosky class is based on what host bone remains to support a cup, not on the size of the radiolucent line alone.
- Assess the anterior and posterior columns, superior dome, medial wall, rim, teardrop, ischium and pelvic continuity separately.
- A porous augment restores a platform for the shell; a cage bridges a discontinuity but needs biological support or stable fixation to survive.
- The hip centre, offset, leg length, cup orientation and soft-tissue tension must be planned with the defect, not after the shell has been fixed.
- CT is essential when metal, migrated hardware, severe medialisation or pelvic discontinuity hides the true three-dimensional defect.
- “Paprosky IIIB includes severe superior migration and often medial wall deficiency or discontinuity; a standard jumbo cup alone is usually not enough.
- “The amount of host-bone contact and the location of that contact matter more than cup size.
- “A cup-cage uses the shell for biological host-bone fixation and the cage for immediate column bridging and liner support.
- “A custom triflange is a patient-specific three-zone fixation strategy, not merely an oversized cup.
Definition and Causes
Acetabular bone loss is the reduction in viable pelvic bone available to remove an implant, support a new shell, restore the hip centre and allow future revision. A defect is cavitary when bone is hollowed but the rim or columns remain, segmental when a wall or column is absent, and combined when both patterns coexist.
Causes. Bone is lost through:
- Particle-induced osteolysis and migration of a loose shell
- Repeated revision and removal of cages, screws, cement or augments
- Periprosthetic fracture and pelvic discontinuity
- Periprosthetic infection and osteomyelitis
- Radiation or metabolic bone disease
- Congenital dysplasia or previous pelvic osteotomy
- Tumour resection or severe pelvic trauma
Describing the defect. The surgeon must describe the defect in terms that change the operation: location, containment, columns, migration, bone quality, pelvic continuity, soft tissue and infection. The anterior and posterior columns, superior dome, medial wall, rim, teardrop, ischium and pelvic continuity are each assessed separately.
Anatomy of Acetabular Fixation
The columns. The anterior column extends from the pubis through the iliac eminence to the superior acetabulum and provides anterior structural support. The posterior column extends from the ischium to the greater sciatic notch and posterior dome; it is close to the sciatic nerve and supports posterior fixation. The two columns are the structural bridges: if both are deficient or mobile, a hemispherical shell has no reliable pelvic ring to hold it.
Dome, rim and medial wall. The superior dome and rim provide the strongest host-bone contact for a shell but are commonly lost in superior migration. The medial wall separates the acetabulum from the pelvic cavity; a deficient wall allows medial migration and threatens intrapelvic structures.
Distal and iliac fixation. The ischium and pubic ramus provide distal screw or cage fixation when the superior rim is absent. The iliac wing provides long screw purchase, but the inner table is adjacent to iliacus and pelvic vessels. The safest screw corridor is the one visible on CT and confirmed intraoperatively; a long screw through a thin or rotated column is a hazard, not a stronger reconstruction.
Hip centre. The hip centre and abductor lever arm determine stability, gait and nerve tension. A high hip centre can be acceptable in selected reconstructions but must be planned with offset and leg length.
Paprosky Classification
The Paprosky class is based on what host bone remains to support a cup, not on the size of the radiolucent line alone.
- Radiographic pattern
- Minimal osteolysis; intact rim and columns; no migration
- Likely host-bone support
- Good circumferential support
- Typical strategy
- Revision shell with screws; graft contained defects
- Radiographic pattern
- Superior bone loss with intact columns and limited migration
- Likely host-bone support
- Superior rim partly deficient but columns support the shell
- Typical strategy
- Porous shell with screws and augment or graft as required
- Radiographic pattern
- Superior rim deficiency with moderate migration
- Likely host-bone support
- Remaining anterior/posterior columns and some dome
- Typical strategy
- Shell plus porous augment or jumbo cup with reliable column fixation
- Radiographic pattern
- Medial wall deficiency and medial migration
- Likely host-bone support
- Columns remain but the floor is deficient
- Typical strategy
- Shell with medial augment, cage or controlled reconstruction; protect pelvic organs
- Radiographic pattern
- Extensive superior and lateral loss with more than about 3 cm migration but an intact Kohler line
- Likely host-bone support
- Some superior dome or columns remain for fixation
- Typical strategy
- Large porous augment plus shell, cup-cage or structural reconstruction
- Radiographic pattern
- Extensive loss with medial migration, absent columns or a disrupted Kohler line; may include discontinuity
- Likely host-bone support
- Minimal host-bone support and possible pelvic ring instability
- Typical strategy
- Cup-cage, distraction, custom triflange, allograft or staged salvage
Type IIIB. It includes severe superior migration and often medial wall deficiency or discontinuity; a standard jumbo cup alone is usually not enough.
Limits of the label. The thresholds and radiographic signs are guides. Severe deformity, metal overlap and pelvic rotation can make the class uncertain; CT and intraoperative assessment override a confident but incorrect label.
Clinical Assessment
History. Document all hip procedures, the primary diagnosis, previous implants and cages, infection organisms and treatment, fractures, dislocation, radiation, pelvic surgery and the timing of leg-length change. Ask about pain on start-up, instability, groin pain, neurological symptoms, walking aids, transfers and the ability to comply with protected loading.
Examination. Inspect gait, shortening, Trendelenburg sign, scars, sinus, flaps and skin adherence, then palpate the greater trochanter, iliac crest and pubic region. Assess hip motion, abductor strength, flexion contracture, sciatic and femoral nerve function and distal pulses. Examine the opposite hip, knee and ankle, because reconstruction changes the entire limb chain.
Infection and biology. Use serum markers, aspiration when feasible, imaging and multiple deep samples. A sinus tract communicates with the implant until proven otherwise. Infection, poor soft tissue, radiation and non-viable bone change the reconstruction. Porous metal does not overcome uncontrolled infection or absent biology.
Medial migration and prior screws can place the iliac vessels, obturator structures, bladder and bowel close to the implant, and CT angiography may be required before extraction. If the cup has migrated medial to the iliopectineal line, a screw is close to the iliac vessels or the patient has prior pelvic vascular surgery, obtain CT angiography and involve vascular surgery before extraction.
Investigations and Planning Measurements
Radiographs. Obtain an AP pelvis, Judet views, a cross-table lateral and serial comparison, and when possible a standing long-leg film to assess limb length and mechanical axis. Evaluate migration relative to the teardrop, Kohler line and superior rim, and inspect the iliopectineal and ilioischial lines, screw breakage, cage hooks, protrusio, femoral stem position and abductor tension.
CT. Thin-slice CT with metal artefact reduction is essential when metal, migrated hardware, severe medialisation or pelvic discontinuity hides the true three-dimensional defect. It should define:
- Cavitary versus segmental loss
- Anterior and posterior column continuity
- Superior rim, medial wall, ischium and pubic ramus
- Chronic or acute pelvic discontinuity
- Bone thickness for screws and flange contact
- The relationship of hardware to iliac vessels, bladder and bowel
- Femoral component position and the planned hip centre
Planning measurements. The hip centre, offset, leg length, cup orientation and soft-tissue tension are planned with the defect, not after the shell has been fixed. Record the existing and intended hip centre, cup inclination and version, leg length, offset, femoral stem relationship, available host-bone contact and screw corridor length. Plan the amount of medialisation or superior placement that the soft tissues can tolerate; the goal is not to force an anatomic centre at the cost of unstable fixation, nerve injury or intrapelvic penetration.
Reconstruction Ladder
Coverage versus fixation. The amount of host-bone contact and the location of that contact matter more than cup size. A cup can be covered by bone or augment but still lack axial or rotational fixation, so the construct is tested mechanically and the remaining columns are secured. A defect with no reliable host-bone contact needs a cage, distraction, custom or staged strategy.
What each construct does. A porous augment restores a platform for the shell; a cage bridges a discontinuity but needs biological support or stable fixation to survive. A cup-cage uses the shell for biological host-bone fixation and the cage for immediate column bridging and liner support. A custom triflange is a patient-specific three-zone fixation strategy, not merely an oversized cup.
- Fixation problem
- Volume loss but rim and columns support a shell
- Reconstruction
- Impaction graft or porous augment with revision shell and screws
- Fixation problem
- Shell lacks a local platform but columns retain support
- Reconstruction
- Porous augment with a shell, structural graft or cage according to location
- Fixation problem
- Limited host-bone contact and migration
- Reconstruction
- Jumbo cup only if real host fixation remains; otherwise augment-shell, cage or distraction
- Fixation problem
- Superior and inferior hemipelvis move independently
- Reconstruction
- Cup-cage, custom triflange or distraction that captures both segments
- Fixation problem
- No safe biological bed for definitive metal
- Reconstruction
- Staged debridement, spacer/dead-space management, coverage and delayed reconstruction
Operative Technique
The exact operation follows the chosen construct, but every reconstruction should follow the same sequence of biological debridement, controlled reduction, fixation and verification.
Acetabular reconstruction sequence
Use the lateral or supine position according to the approach and secure the pelvis for stable imaging. Prep from the costal margin to the foot when an extensile approach, vascular exposure or flap may be required. Keep the opposite limb available for leg-length and hip-centre comparison, and coordinate blood conservation and thrombosis planning.
Confirm that an AP pelvis and oblique views of both columns can be obtained. Have shell, augments, cage, cup-cage, screws, graft and a rescue implant available, and confirm implant side, cup orientation, bearing and planned screw corridors. Review the CT angiography or vascular advice before manipulating hardware near the iliac vessels.
Give antibiotics after cultures when the patient is stable and infection must be characterised; use therapeutic antibiotics when infection is established. Confirm the defect class, pelvic continuity, soft-tissue plan and expected postoperative loading. Prepare graft or porous surfaces only after all non-viable tissue and cement planned for removal have been identified.
Use the safest previous scar, preserve skin bridges and excise a sinus tract en bloc. Expose the acetabulum and columns enough to seat the chosen construct without stripping all residual periosteum. In a scarred posterior approach, identify the sciatic nerve and control retractors under direct vision.
Remove liner, shell, cage, cement, screws and loose graft, protecting the femoral component if it will be retained and infection allows. Obtain multiple deep samples and histology, then debride membrane, granuloma, purulence and non-viable bone. Define the remaining anterior and posterior columns, superior rim, medial wall, ischium and pubis.
Freshen only to viable bleeding bone and preserve the structural columns; contain cavitary defects with graft or a porous augment according to the plan. Trial the shell, augment, cage or custom component, and confirm the planned hip centre and that the construct contacts real host bone. Mark and drill the safest screw corridors with stops or navigation; do not rely on freehand depth estimation in a distorted pelvis.
Reduce the hemipelvis or seat the shell under controlled force, avoiding a shell position that obtains apparent coverage only by excessive medialisation or superior migration. Trial the femoral head and liner, checking leg length, offset, version, abductor tension, impingement and sciatic nerve tension. If a discontinuity is present, ensure both hemipelvic segments are captured before final fixation.
Use controlled retractors, protect the pelvic cavity and confirm every screw remains within a known bony corridor. Stop and obtain vascular or general-surgical help if the implant or screw is close to a vessel or organ. Do not lengthen the limb aggressively in a scarred hip with pre-existing sciatic risk.
Obtain the planned host-bone fixation with a porous shell, augment, screws and/or cage. For a cup-cage, stabilise the shell and cage before cementing the liner; for a custom triflange, seat and fix all three flanges; for distraction, apply the validated distraction and shell technique. Add graft to support biological incorporation, not to mask a rocking implant or uncontrolled infection.
Obtain an AP pelvis and orthogonal or oblique views of the columns and all critical screws. Confirm cup centre, inclination, version, femoral length and offset, component seating, cage or flange stability and the absence of intrapelvic breach. Revise unsafe hardware before closure; postoperative imaging cannot undo a preventable injury.
Close durable fascia and skin, using flap or negative-pressure support when the envelope is compromised. Use toe-touch or partial weight bearing and approach and bearing precautions until incorporation is demonstrated. Continue infection treatment, thrombosis prevention, neurovascular checks and transfer training.
Complications and Failure Management
- Clues
- Sinus, drainage, fever, positive cultures, painful loosening
- Response
- Cultures and staged debridement; do not retain contaminated metal
- Clues
- Early instability or recurrent reduction
- Response
- Reduce, assess nerve and analyse cup, femur, offset, abductors and liner; revise cause
- Clues
- New groin pain, vascular or visceral symptoms, CT breach
- Response
- CT angiography and specialist control; never blindly remove high-risk hardware
- Clues
- Persistent pain, pelvic motion, progressive migration
- Response
- Exclude infection, obtain CT and revise only with a stable column-bridging plan
- Clues
- Broken screws, loss of cup position or metal fatigue
- Response
- Treat pelvic stability, host bone and infection together; isolated liner exchange is inadequate
Guidelines, Registries & Global Practice
Global evidence. The Paprosky system remains widely used for communication, but evidence for each reconstruction is largely from cohort series. Porous metal augments and shells have expanded the options for severe loss; cup-cage, distraction and custom triflange address pelvic discontinuity. No technique eliminates infection, dislocation, nerve or visceral risk.
Evidence-informed rules. What the cohort evidence supports:
- Describe defect location, containment, columns, pelvic continuity, bone quality and infection rather than recording only a class.
- Use CT for severe loss, migration, hardware overlap and discontinuity; CT angiography for vessel risk.
- Obtain stable host-bone fixation and bridge the columns when the ring is unstable.
- Restore hip mechanics without excessive medialisation or lengthening.
- Stage infection and preserve the soft-tissue envelope for future reconstruction.
Registries. Arthroplasty registries such as NJR, AJRR, AOANJRR and Scandinavian registries capture acetabular revision burden but often do not record the defect class or precise reconstruction. Centres should record Paprosky class, discontinuity, implant, bearing, infection, migration, union and reoperation.
Global practice. Where porous augments, navigation and custom manufacture are available, complex defects can be planned more precisely. Where they are not, a well-executed cage, structural graft or staged reconstruction may be safer than an unsupported shell. The fundamentals remain stable: viable bone, secure fixation, safe corridors, infection control and a usable hip centre.
MCQ Practice Points
Q: How do you separate a Paprosky IIC from a type III defect?
A: IIC is a medial problem; III is a rim and column problem. IIC is dominated by medial wall deficiency and medial migration with the columns still providing support — Paprosky's original series treated it with a wafer femoral head graft to the medial wall. Type III involves extensive segmental loss, migration and limited host bone available for fixation, and IIIB may include pelvic discontinuity. The distinction is load-bearing because in IIC there is still a supporting rim to seat a shell on, and in III there may not be.
Q: Having assigned a Paprosky grade, what actually determines the reconstruction?
A: Where the remaining viable host bone is, and whether it can give stable axial and rotational fixation. The class is a language, not an implant prescription. Paprosky's own paper makes this the determinant of success — "adequate remaining host bone must be present to ensure bone ingrowth" — and it is why two IIIA defects can need different constructs.
Q: How much confidence should you place in a Paprosky grade read off a preoperative radiograph?
A: Less than most people assume, and this is the high-yield answer. Driscoll 2024 (PMID 39311938) found inter-rater agreement only moderate at every training level (κ 0.42–0.50) — residents, fellows and attendings alike — agreement on treatment selection mostly poor (κ 0.02–0.44), and agreement between the preoperative and intraoperative classification only fair (κ 0.25–0.36).
Yu 2013 (PMID 23412731) is the more optimistic study and its optimism is conditional: weighted kappa rose from 0.56 to 0.79 only after three teaching sessions, and did not improve without teaching at all. So: the system is valid, it is reliable only with standardised landmarks and explicit training, and the grade you assign preoperatively agrees only fairly with what you will find. Consent for the range, and have augments, a cage and a discontinuity plan available whatever the film suggested.
Q: Explain the mechanics of a cup-cage.
A: The porous shell seeks biological fixation in host bone; the cage bridges the columns and gives immediate support for a cemented liner. They act as one construct, not two devices. The reason this beat the cage alone is that a cage only spans the defect — Beckmann's review of 1,959 trabecular metal against 1,541 ring reconstructions found significantly lower loosening with trabecular metal across all grades, with the severe defects benefiting most. Bridging does not improve as bone loss worsens; ingrowth does.
Q: When would you use a custom triflange, and what should you warn the patient about?
A: For severe three-dimensional loss or chronic pelvic discontinuity, when CT-defined iliac, ischial and pubic fixation can capture both hemipelvic segments and other constructs are not credible. DeBoer's series (PMID 17403808, 20 hips at a mean of ten years) showed no broken screws, no migration and no component revised — even where the discontinuity never united, so radiographic non-union alone does not condemn a stable construct. Warn about what actually went wrong: five patients dislocated and 11 of 18 still needed a walking aid.
Q: What must you exclude before extracting a migrated component?
A: A migrated component or screw may lie against the iliac vessels, bladder or bowel. Obtain CT angiography and arrange specialist vascular control before extraction whenever the relationship is uncertain. This is the error with the worst consequence on this page, and it is entirely preventable by imaging.
Exam Viva Scenarios
Practise clinical reasoning and management decisions out loud
“A 68-year-old has a loose shell with superior and lateral bone loss, more than 3 cm of migration, an intact Kohler line and an intact posterior column. Infection work-up is negative. How do you reconstruct the acetabulum?”
“A 76-year-old has a loose cup migrated medially. A screw projects through the medial wall and CT suggests it is close to the external iliac vessels. The patient has groin pain but palpable pulses. What is your plan?”
“A patient has painful migration and broken cage screws three years after cup-cage reconstruction. CT shows a mobile chronic discontinuity, a deficient posterior column and no abscess. How do you plan the second salvage?”
Describe
- Cavitary versus segmental; anterior/posterior column, rim, dome, medial wall, ischium and pubis
- Migration, bone quality, pelvic continuity, infection and soft-tissue coverage
- Paprosky I to IIIB communicates the remaining host-bone support
- CT is essential when metal, migration or discontinuity obscures the defect
Reconstruct
- Contained: graft or porous augment plus revision shell
- Segmental: porous augment-shell, cage or structural graft
- Large uncontained: jumbo cup only with real support; otherwise cup-cage, distraction or custom
- Discontinuity: stabilise both hemipelvic segments
Operative sequence
- Position and image the pelvis, vessels and full limb
- Approach safely, culture, remove failed hardware and debride to viable bone
- Prepare columns and planned screw corridors; protect sciatic nerve and pelvic organs
- Reduce, restore centre/length/offset/version, fix the shell/augment/cage and image
- Close with durable coverage and protect weight bearing
Complications
- Infection, dislocation, migration, screw breach, nerve/vascular/visceral injury and nonunion
- Never remove a vessel-adjacent screw blindly
- A shell must have real host-bone fixation, not only coverage
- A discontinuity requires ring stability, not an isolated cup
Evidence Base
A classification page owes the reader its reliability figures, and this one carried none. Both cards below that were here before have been rebuilt: one summarised the classification without a single number, and the other attached DeBoer's custom-triflange series to the title "Porous metal augments in acetabular revision" — a paper that does not exist, while the page's own reference 3 named DeBoer's real paper correctly. The two reliability studies are new and they are the most important cards here.
Acetabular Defect Classification and Surgical Reconstruction in Revision Arthroplasty: A 6-Year Follow-Up Evaluation
- The origin of the classification: 147 cemented acetabular components revised to cementless hemispherical press-fit shells between 1982 and 1988, average follow-up 5.7 years (range 3 to 9)
- The types were defined by what reconstruction they required, not by appearance alone - Type 1 particulate graft; Type 2A and 2B progressive superior loss needing particulate or femoral head bulk graft or cup superiorisation; Type 2C medial wall repair with a wafer femoral head graft; Type 3A and 3B progressive superior RIM deficiency needing structural distal femur or proximal tibia allograft
- SIX OF 147 COMPONENTS (4.0 PER CENT) WERE UNSTABLE AND WARRANTED REVISION - AND ALL SIX WERE TYPE 3B, which is the single most useful outcome number in the paper
- Moderate lateral allograft resorption was seen radiographically, but host-graft union was confirmed at revision
- The authors' stated determinants of success: size, orientation and fixation method of the allograft, plus ADEQUATE REMAINING HOST BONE to permit ingrowth
Validity and Reliability of the Paprosky Acetabular Defect Classification
- The validation the classification had gone without for nineteen years: preoperative radiographs from 83 patients undergoing 85 acetabular revisions, classified by four observers and compared against QUANTITATIVE INTRAOPERATIVE MEASUREMENTS
- Radiographic evaluation showed statistically significant relationships with intraoperative measurement of anterior, medial and superior defect size - so the system is measuring something real
- THE HEADLINE IS CONDITIONAL AND THE CONDITION IS TEACHING. Weighted kappa rose from 0.56 to 0.79 in observers given THREE teaching sessions, and from 0.49 to 0.65 in those given ONE
- INTEROBSERVER RELIABILITY DID NOT IMPROVE WITHOUT TEACHING - repetition alone achieved nothing
- The authors' conclusion is explicitly qualified: the system is valid and shows good reliability WHEN COMBINED with standardised definitions of radiographic landmarks and a structured analysis
Reliability and Validity of the Paprosky Classification for Acetabular Bone Loss Based on Level of Orthopedic Training
- 74 patients with intraoperatively confirmed Paprosky types (I = 24, II = 27, III = 23) classified from preoperative radiographs by six raters - two residents, two fellows and two attendings - twice, 14 days apart
- INTER-RATER AGREEMENT WAS ONLY MODERATE AT EVERY TRAINING LEVEL, kappa 0.42 to 0.50 - experience did not rescue it
- AGREEMENT ON TREATMENT SELECTION WAS MOSTLY POOR: kappa 0.02 to 0.44
- THE FINDING THAT MATTERS MOST FOR PLANNING: agreement between the PREOPERATIVE classification and the INTRAOPERATIVE one was only FAIR, kappa 0.25 to 0.36
- Agreement between the treatment planned from radiographs and the treatment actually performed was likewise only fair, kappa 0.21 to 0.39
- The authors call for advanced imaging and alternative classifications to be investigated
Revision Total Hip Arthroplasty for Pelvic Discontinuity
- 28 consecutive patients (30 hips) with pelvic discontinuity reconstructed with a CUSTOM-MADE porous-coated TRIFLANGE prosthesis built from a CT-derived three-dimensional hemipelvis model; 20 hips in 18 patients followed a mean of TEN YEARS
- Definite healing of the discontinuity, shown by bridging callus, in 18 of 20 hips
- NO BROKEN SCREWS AND NO IMPLANT MIGRATION - even in the hips where the discontinuity did NOT heal, which is the mechanically striking result
- NO COMPONENT WAS REVISED at a mean of ten years
- Harris hip score improved from 41 to 80
- The costs sit in the soft tissues, not the fixation: FIVE patients had one or more dislocations, one had a partial sciatic nerve palsy that resolved, and 11 of 18 required ambulatory aids afterwards
Loosening After Acetabular Revision: Comparison of Trabecular Metal and Reinforcement Rings - A Systematic Review
- The largest comparison of the two reconstruction philosophies: 1,541 revision-ring cases (mean follow-up 5.7 years) against 1,959 trabecular metal cases (mean follow-up 3.7 years)
- Failure rates were compared with a logistic regression model ADJUSTED for the difference in follow-up duration
- TRABECULAR METAL SHOWED SIGNIFICANTLY LOWER LOOSENING THAN REVISION RINGS ACROSS ALL DEFECT GRADES, including severe defects and pelvic discontinuity
- THE SEVERE DEFECTS BENEFITED MOST - the advantage widened rather than narrowed as bone loss increased, which is the opposite of what a purely mechanical bridging device would predict
- Read alongside Issack's review: the argument for porous tantalum is biological - higher porosity, high friction coefficient and an elastic modulus closer to bone give better ingrowth and host-bone preservation than titanium mesh or cobalt chromium
References
- Paprosky WG, Perona PG, Lawrence JM. Acetabular defect classification and surgical reconstruction in revision arthroplasty. A 6-year follow-up evaluation. J Arthroplasty. 1994;9(1):33-44. PMID: 8163974. DOI: 10.1016/0883-5403(94)90135-x.
- Bradford MS, Paprosky WG. Acetabular defect classification: a detailed radiographic approach. Semin Arthroplasty. 1995;6(2):76-85. PMID: 10155692.
- DeBoer DK, Christie MJ, Brinson MF, et al. Revision total hip arthroplasty for pelvic discontinuity. J Bone Joint Surg Am. 2007;89(4):835-840. PMID: 17403808. DOI: 10.2106/JBJS.F.00313.
- Issack PS. Use of porous tantalum for acetabular reconstruction in revision hip arthroplasty. J Bone Joint Surg Am. 2013;95(21):1981-1987. PMID: 24196469. DOI: 10.2106/JBJS.L.01313.
- 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 Supple A):36-42. PMID: 25381406. DOI: 10.1302/0301-620X.96B11.34455.
- Yu R, Hofstaetter JG, Sullivan T, Costi K, Howie DW, Solomon LB. Validity and reliability of the Paprosky acetabular defect classification. Clin Orthop Relat Res. 2013;471(7):2259-2265. PMCID: PMC3676616. PMID: 23412731. DOI: 10.1007/s11999-013-2844-7.
- 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. PMCID: PMC3254733. PMID: 21997785. DOI: 10.1007/s11999-011-2126-1.
- Beckmann NA, Weiss S, Klotz MC, et al. Loosening after acetabular revision: comparison of trabecular metal and reinforcement rings. A systematic review. J Arthroplasty. 2014;29(1):229-235. PMID: 23719095. DOI: 10.1016/j.arth.2013.04.035.
- Driscoll DA, Ricotti RG, Malahias MA, et al. Reliability and validity of the Paprosky classification for acetabular bone loss based on level of orthopedic training. Arch Orthop Trauma Surg. 2024;144(9):4267-4273. PMID: 39311938. DOI: 10.1007/s00402-024-05524-x.
Corrections made in August 2026 after resolving every entry against PubMed. Four entries were wrong. Reference 2 named "Paprosky WG, Bradford MS, Younger TI. Classification of bone defects in the acetabulum and its implication for revision total hip arthroplasty. Instr Course Lect. 1994;43:241-247" — no paper of that title exists; the detailed radiographic companion paper is Bradford & Paprosky in Semin Arthroplasty 1995, now reference 2. Reference 7 named "De Martino I, D'Apolito R, Sculco PK, et al. 2D and 3D-printed custom triflange acetabular components... Hip Int. 2019;29:591-599" — not resolvable. Reference 8 attributed to Taunton the title "The use of custom triflange acetabular components in the management of severe acetabular bone loss" at 470:484-492; his real 2012 CORR paper is "Pelvic discontinuity treated with custom triflange component: a reliable option" at 470(2):428-434. Reference 10 named "Ranawat AS, Rasquinha VJ, Howard H, et al. Revision total hip arthroplasty for pelvic discontinuity. J Arthroplasty. 2005;20(4 Suppl 2):96-100" — not resolvable, and its title is identical to reference 3's, which is a real DeBoer paper. The two unresolvable slots have been filled with the reliability studies this page most needed.