A revision-like arthroplasty operation with fracture, infection, bone-loss and abductor risks
- Conversion THA has higher infection, fracture, dislocation, abductor and revision risk than routine primary THA.
- Obtain full-length femoral imaging and plan every screw, nail, cement fragment and stress riser before choosing the stem.
- A sinus or suspicious nonunion requires an infection pathway; a normal CRP does not prove aseptic failure.
- The femoral neck, greater trochanter and abductor mechanism may be absent or distorted, so a standard primary stem and direct anterior plan may be unsafe.
- Counsel about possible osteotomy, long stem, trochanteric fixation, staged surgery, leg-length correction and postoperative restrictions.
- “The key difference from primary THA is altered anatomy plus retained hardware and stress risers.
- “Remove a cephalomedullary nail or plate in the planned sequence; do not create a femoral fracture by extracting a broken screw or nail blindly.
- “A long revision stem should bypass screw holes, osteotomy and fracture by a sufficient length and obtain distal fixation.
- “If infection is found, stop the conversion and stage the reconstruction rather than cementing through a contaminated femur.
Definition and Indications
Conversion THA is total hip arthroplasty performed after failed internal fixation of a proximal femoral or acetabular fracture. The failure may be nonunion, malunion, collapse, avascular necrosis, post-traumatic arthritis, implant cut-out, broken hardware, infection or painful hardware with a non-reconstructable hip.
Why it is not a routine primary arthroplasty. Hardware removal, distorted anatomy and compromised bone make the operation revision-like: the femoral neck, greater trochanter and abductor mechanism may be absent or distorted, the femur carries retained hardware and stress risers, and failed fixation can harbour low-grade infection. Infection, fracture, dislocation, abductor and revision risks are all higher than after routine primary THA, so the patient is counselled about possible osteotomy, a long stem, trochanteric fixation, staged surgery, leg-length correction and postoperative restrictions.
The indications. The patterns that most often come to conversion:
- Femoral neck nonunion or avascular necrosis after screws, a dynamic hip screw or other fixation.
- Intertrochanteric or subtrochanteric nonunion with varus collapse, loss of the femoral neck or a failed cephalomedullary nail.
- Post-traumatic acetabular or femoral-head degeneration with retained fixation that cannot be safely left in place.
- Cut-out, implant breakage, migration or a painful malunion that prevents useful hip reconstruction.
- Selected infection-controlled cases after staged debridement and fracture-healing assessment.
The alternatives. The indication should explain why THA is preferred over revision fixation, a valgus or proximal femoral osteotomy, hemiarthroplasty, fusion or resection. A patient with a reconstructable nonunion and a preserved joint may not need conversion THA.
Anatomy and Hazards After Fixation
Femoral neck and head. Collapse shortens the limb and changes the hip centre, and screws may have penetrated the joint or damaged the head.
Greater trochanter and abductors. Lateral plates, cables, nonunion and previous approaches can disrupt the abductor lever arm. Greater trochanter nonunion, lateral plate removal and gluteal scarring increase limp and dislocation risk, so trochanteric fixation or a soft-tissue reconstruction is planned in advance.
The canal and its stress risers. Nails and cement may have enlarged, bowed or blocked the proximal femoral canal, and every old screw hole and locking bolt is a stress riser. A primary stem can perforate the canal or fail to bypass those risers; the revision stem must bypass or protect each one.
Sciatic nerve. Posterior scars, length restoration and retractors put it at risk. Document baseline function and avoid excessive acute lengthening.
Femoral vessels and soft tissues. Previous surgery may leave the iliopsoas, femoral vessels and capsule adherent, particularly where hardware sits anteriorly.
Acetabulum. Post-traumatic bone loss, screws and protrusio can make the acetabular side a revision problem too.
Assessment and Examination
History. Record the fracture pattern, the original reduction, the implant type and every revision, the weight-bearing history, any infection or wound drainage and the antibiotics given, falls, head collapse, where the pain is, any change in leg length and the pre-injury function. Ask about current walking aids, stairs at home, hip and spine disease and what the patient expects from the operation.
Examination. Inspect the scars, any sinus, trochanteric prominence and limb shortening, then watch the gait, the Trendelenburg sign and transfers. Palpate the greater trochanter, the fracture site, the hardware and the groin. Measure flexion, extension, abduction and rotation and look for a fixed flexion or external rotation deformity.
Document sciatic, femoral and peroneal nerve function, the pulses and skin perfusion, and examine the opposite hip, the knee and the ankle. Test the abductor mechanism and note whether a greater trochanteric fragment moves independently.
Infection. Failed fracture fixation can harbour low-grade infection, so obtain serum inflammatory markers, aspirate the hip or the nonunion when feasible, and plan multiple deep tissue and membrane samples with histology at surgery. A draining sinus or a purulent nonunion is infection until proven otherwise; a negative aspiration does not override strong clinical or radiographic suspicion, and a normal CRP does not prove aseptic failure. When infection is established the reconstruction is staged.
Imaging and Templating
Radiographs. Obtain an AP pelvis, AP and lateral views of the full femur including the knee, and long-leg alignment films when shortening or deformity is substantial. Compare them with the old films to understand implant migration and fracture healing: each generation of hardware has left its own holes, and the stem must bypass every generation, not just the implant still in place. Radiographs and CT together show screw trajectories, nail locking bolts, cement, cortical windows, nail bow and distal stress risers.
CT with metal artefact reduction is useful for:
- nonunion geometry and malunion
- femoral head collapse, intra-articular screw penetration and acetabular bone loss
- nail bow, distal locking bolts, cement, cortical windows and stress risers
- canal patency and distal fixation length
- a suspected infection cavity or sequestrum
- vessel or organ proximity when hardware has migrated
Templating runs from the femur upward:
- plan the order of hardware removal and whether any implant can be left temporarily
- choose a stem that bypasses every screw hole, osteotomy and fracture
- restore hip centre, offset, version and length without sciatic over-lengthening
- plan calcar replacement, a modular proximal body, cable-plate or trochanteric fixation
- have extraction tools for broken screws and a full-removal rescue strategy
The fracture plan. Extraction is a separate operation within the arthroplasty, and a broken screw can become a cortical fracture if forced. Have cerclage, a long revision stem, a plate, cables, a strut graft, flexible extraction tools and an osteotomy option ready before the incision.
Approach and Reconstruction Choice
The approach depends on the scars, the hardware, the deformity, the acetabular side and whether an osteotomy is needed. A posterior or lateral approach may facilitate nail removal and trochanteric reconstruction. An anterior approach may be possible in selected femoral neck failures, but it does not eliminate the need to map posterior hardware and distal stress risers, and a primary approach that destroys the only functioning abductor is not a safe shortcut.
- Preferred strategy
- Cementless or cemented THA with planned hardware removal
- Important modification
- Check abductor and calcar; use a modular or standard stem only if the canal is safe
- Preferred strategy
- Long revision stem or proximal femoral reconstruction
- Important modification
- Fix trochanteric fragment and bypass the nonunion and screw holes
- Preferred strategy
- Long diaphyseal-engaging stem with cables/plate or osteotomy
- Important modification
- Map nail extraction and bypass the fracture by reliable distal fixation
- Preferred strategy
- Revision acetabular shell, augment, cage or other reconstruction
- Important modification
- Plan both sides as a revision THA, not an isolated femoral conversion
- Preferred strategy
- Staged removal, debridement and temporary antibiotic construct
- Important modification
- Delay definitive THA until infection and coverage are controlled
The trochanter and the calcar. The table sets the strategy by failure pattern; the decisions beneath it concern the trochanter and the calcar. A mobile trochanter is fixed: the abductor fragment is the dislocation risk after intertrochanteric failure. A canal with no calcar left takes a long or calcar-replacing stem. A long cemented stem is a reconstruction choice, not a default, and whatever the stem, it must bypass or protect the distal locking hole a nail leaves behind, which a primary stem will not cover.
Operative Technique: PIPADRAW
Conversion THA sequence
Lateral or supine according to the approach, with the pelvis secured and the entire femur and foot accessible. Prep from the iliac crest to the foot, taking in old lateral or distal locking incisions and any potential osteotomy or flap field. Protect the pressure points and coordinate blood conservation, cell salvage and nerve monitoring when deformity or lengthening is substantial.
Confirm AP and lateral images of the hip, the full femur and the knee, and verify the implant type, the locking-bolt positions, cement, canal bow and the planned stem bypass before the incision. Broken-screw extraction tools, flexible reamers, nail extractors, cerclage, cables, plates and revision stems are ready, and a temporary spacer or staged pathway is available in case infection is encountered.
When the patient is stable and infection must be characterised, antibiotics wait until the deep samples are taken; sepsis is treated immediately. Confirm the hardware-removal sequence, the acetabular plan, the stem plan, the trochanteric fixation and the postoperative weight-bearing restrictions. Prepare the limb and skin so that every sinus can be excised and the final closure remains viable.
Use the safest previous incision or an extensile approach that preserves skin bridges, and excise sinus tracts en bloc. Expose the greater trochanter, the fracture or nonunion and the hardware far enough to control extraction while protecting the abductors and the sciatic nerve. Do not force the hip into dislocation when screws or nail fragments can be removed through a planned separate window.
Locking bolts and proximal hardware come out before the nail is extracted; plates and screws come out in the planned sequence, with fluoroscopy for buried or broken components. A cold-welded or broken screw is taken with a trephine or an extraction system rather than excessive torque against thin cortex. Take multiple deep samples and histology before antibiotics when appropriate, culture the membrane, and debride infected membrane and non-viable tissue.
Remove the femoral head or the failed neck segment and prepare the acetabulum, treating acetabular bone loss with the appropriate revision strategy. Prepare the canal only after the metal is out: identify the true femoral canal, remove cement or debris, and ream along the canal while protecting the cortex. Freshen the nonunion only to viable bone and prepare the greater trochanter for cable, plate or abductor repair.
Trial the stem and head, checking hip centre, offset, length, version, abductor tension and sciatic nerve tension, and compare foot progression and knee and ankle clearance with the opposite limb. A long-standing shortened hip may not tolerate complete anatomical length restoration. Test stability through flexion, adduction and rotation and assess the trochanteric fragment and the soft-tissue repair.
Bypass every screw hole, cortical window, fracture and nonunion with the planned revision stem, and cerclage before stem insertion if a crack is likely. Avoid the excessive traction or acute lengthening that can injure the sciatic nerve, and protect the femoral vessels during anterior or medial dissection. Preserve viable abductors and soft tissue.
Insert the selected cemented or uncemented stem with stable distal fixation and the planned version, using a long stem or modular body when proximal bone is deficient. Fix the greater trochanter or the nonunion with cables, plate, graft or a strut as indicated and reconstruct the capsule and abductors. Place the acetabular shell, liner and femoral head, then repeat the stability, length and offset checks.
Obtain AP and lateral images of the pelvis and the full femur including every old hardware site, and check stem bypass, cortical cracks, trochanteric fixation, cup position, head centre, length, offset and the absence of retained loose metal. A fracture or an unstable trochanter found now is stabilised before closure and the postoperative loading plan adjusted.
Repair the abductors, capsule and fascia without tension, close the old hardware windows and protect the skin bridges. Hip precautions and protected weight bearing follow the stem, the fracture and the trochanteric fixation, and transfer training and thrombosis prevention begin. Antibiotics continue according to the cultures, with monitoring for early infection, fracture, dislocation and nerve dysfunction.
Complications and Salvage
- Clues
- Drainage, sinus, fever, positive cultures or persistent nonunion pain
- Response
- Cultures, imaging and infection-team review
- Salvage
- Debridement and staged implant removal/reconstruction
- Clues
- Cortical crack, loss of stem stability or deformity
- Response
- Reduce and cable/plate; image full femur
- Salvage
- Long stem bypass, fracture fixation and protected loading
- Clues
- Early instability, abductor deficiency or malversion
- Response
- Reduction, sciatic exam and mechanical imaging
- Salvage
- Correct stem/cup/offset/soft tissue; use dual mobility or constraint selectively
- Clues
- Foot drop, sensory loss or severe pain
- Response
- Check length, retractors, haematoma and hardware
- Salvage
- Remove causative compression or revise excessive lengthening; rehabilitate
- Clues
- Trendelenburg gait, lateral pain or fragment migration
- Response
- Assess fixation and abductor continuity
- Salvage
- Revision cable-plate/graft and abductor repair
- Clues
- Progressive shortening, thigh pain or radiolucency
- Response
- Exclude infection and image full femur
- Salvage
- Revise with stable distal fixation and bypass stress risers
Postoperative Care and Outcomes
Weight bearing depends on the weakest element, whether that is the stem fixation, the trochanteric repair, the nonunion, a fracture or the acetabular reconstruction, and not on a primary-THA protocol. A simple femoral neck conversion may progress faster than a subtrochanteric nonunion with an extended osteotomy. Use a brace or abduction pillow when the soft tissues require it.
Surveillance. Serial radiographs include the whole femur, and the postoperative check is a full-femur film rather than a hip snapshot: has the stem bypassed every hole, is the trochanter where it was left, does any broken screw remain. Later films are read for stem subsidence, periprosthetic fracture, retained metal, trochanteric union, cup migration, dislocation and progressive osteolysis. New or persistent pain requires assessment of infection, fracture, loosening and the abductors; it is not automatically postoperative adaptation.
Guidelines, Registries & Global Practice
Global evidence. Conversion THA after failed fixation has higher complication risk than primary THA, especially after intertrochanteric and subtrochanteric failure. Evidence comes from comparative cohorts and systematic reviews, with outcomes influenced by fracture pattern, implant, timing, infection, deformity and surgeon experience.
Practice principles
- Treat the case as a revision arthroplasty with an infection and fracture work-up.
- Map and remove hardware in a controlled sequence; protect the femur from stress-riser fracture.
- Use a stem that bypasses holes, nonunion and cortical windows and obtains real distal fixation.
- Restore hip mechanics without excessive sciatic lengthening and reconstruct abductors/trochanter.
- Obtain multiple cultures and stage infection rather than converting a contaminated nonunion directly to THA.
Registries. Hip arthroplasty registries report conversion THA incompletely because the index fracture fixation and indication may not be captured in the same record. Centres should record fracture type, fixation, nonunion, infection, hardware, stem, osteotomy, dislocation, fracture and reoperation.
Global practice. The operation may be performed with standard or modular stems, cemented reconstruction or staged revision depending on resources. A safe plan includes extraction tools, imaging, fracture fixation, cultures and a postoperative rehabilitation pathway wherever it is performed.
MCQ Practice Points
Q: Why does conversion THA after failed fixation carry higher risk than primary THA? A: Retained hardware, distorted anatomy, occult infection, nonunion, abductor damage, bone loss, limb shortening and femoral stress risers make it a revision-like operation.
Q: What must be imaged before conversion THA? A: The pelvis and the entire femur including the knee. Plan every screw, locking bolt, cement fragment, canal bow and stress riser.
Q: What is the stem rule in conversion THA? A: Bypass every screw hole, osteotomy, fracture and nonunion with a stem that obtains reliable distal fixation. A primary stem may not bypass the risk.
Q: What intraoperative finding changes the plan immediately? A: A sinus, purulence, positive deep cultures or an unsafe tissue envelope. Stop definitive conversion and stage infection control.
Q: What is the commonest soft-tissue failure after conversion? A: Trochanteric nonunion or abductor deficiency causing limp and dislocation. Plan trochanteric fixation and abductor repair rather than accepting a bare or mobile fragment.
Total hip arthroplasty after failed internal fixation of proximal femoral fractures
- 102 conversion THAs (1987-2008) after failed internal fixation of hip fracture: 39 intertrochanteric, 63 femoral neck
- Failure aetiology: osteonecrosis 35, arthritis 32, early fixation failure 25, nonunion 10
- Early surgical complications in 12 of 102 (11.8%): 5 dislocations (4.9%), 4 periprosthetic fractures (3.9%), 2 haematomas, 1 infection
- Complication rates exceed those of primary arthroplasty - the revision-like risk profile is the core message
Complications in conversion arthroplasty methods for failed intertrochanteric fracture fixation: a systematic review and meta-analysis
- Meta-analysis of five studies: 138 conversion arthroplasties with 49 complications; mean age 73 (32-96)
- Mean interval from fixation failure to conversion 11 months; mean operative time 132 minutes
- Complication distribution did not differ by method: cemented THA 4.1%, uncemented THA 81.6%, hybrid 2.0%, hemiarthroplasty 12.2% (all non-significant)
- The choice of conversion method did not influence the complication rate
Exam Viva Scenarios
Practise clinical reasoning and management decisions out loud
“A 71-year-old has a broken cephalomedullary nail, varus subtrochanteric nonunion and severe shortening. The hip has secondary arthritis. There is no sinus, but CRP is mildly raised. How do you plan conversion THA?”
“A 58-year-old has painful femoral neck nonunion, head collapse and retained cannulated screws. The greater trochanter and abductor mechanism are intact. What is your operation?”
“During conversion THA for an intertrochanteric nonunion, the tissue is friable and two deep samples grow the same organism. A long stem is already trialled but not cemented. What is your next step?”
Assess
- Fracture pattern, nonunion/malunion, head collapse, infection, hardware, shortening and abductors
- Serum markers, aspiration when feasible, multiple deep cultures and histology
- AP pelvis plus AP/lateral full femur including knee; CT for canal and hardware
- Document sciatic/femoral/peroneal function and vascularity
Plan
- Hardware extraction sequence and broken-screw/nail tools
- Stem bypass of all holes, nonunion, osteotomy and stress risers
- Hip centre, offset, length, version, trochanter and abductor repair
- Long/modular stem, cerclage, plate, graft, staged infection and fracture rescue
PIPADRAW
- Position and image the complete femur; prepare cultures and extraction
- Approach through scars, remove hardware in sequence and protect abductors
- Debride/culture, prepare acetabulum and true femoral canal
- Trial mechanics, insert bypass stem, fix trochanter, image and protect loading
Failure
- Infection: stop definitive conversion and stage
- Fracture: cable/plate and bypass with long stem
- Dislocation: analyse cup, stem, offset, version and abductors
- Nerve palsy: assess length, retractors, haematoma and hardware
References
- Archibeck MJ, Carothers JT, Tripuraneni KR, et al. Total hip arthroplasty after failed internal fixation of proximal femoral fractures. J Arthroplasty. 2013;28(1):168-171. PMID: 22682040. DOI: 10.1016/j.arth.2012.04.003.
- Mortazavi SMJ, Greenky M, Bican O, et al. Total hip arthroplasty after prior surgical treatment of hip fracture: is it always challenging? J Arthroplasty. 2012;27(1):31-36. PMID: 21798695.
- Haidukewych GJ, Berry DJ. Hip arthroplasty for salvage of failed treatment of intertrochanteric hip fractures. J Bone Joint Surg Am. 2003;85(5):899-904. PMID: 12728042. DOI: 10.2106/00004623-200305000-00019.
- Tabsh I, Waddell JP, Morton J. Total hip arthroplasty for complications of proximal femoral fractures. J Orthop Trauma. 1997;11(3):166-169. PMID: 9181498. DOI: 10.1097/00005131-199704000-00005.
- Moon NH, Shin WC, Kim HJ, et al. Cementless total hip arthroplasty following failed internal fixation for femoral neck and intertrochanteric fractures. Injury. 2019;50(3):713-719. PMID: 30670321.
- Laffosse JM, Molinier F, Tricoire JL, Bonnevialle N, Chiron P, Puget J. Cementless modular hip arthroplasty as a salvage operation for failed internal fixation of trochanteric fractures in elderly patients. Acta Orthop Belg. 2007;73(6):729-736. PMID: 18260485.
- Della Valle CJ, Berger RA, Rosenberg AG, Jacobs JJ, Sheinkop MB, Paprosky WG. Extended trochanteric osteotomy in complex primary total hip arthroplasty. A brief note. J Bone Joint Surg Am. 2003;85(12):2385-2390. PMID: 14668509.
- Paprosky WG, Weeden SH, Bowling JW Jr. Component removal in revision total hip arthroplasty. Clin Orthop Relat Res. 2001;(393):181-193. PMID: 11764348. DOI: 10.1097/00003086-200112000-00021.
- Parvizi J, Zmistowski B, Berbari EF, et al. New definition of periprosthetic joint infection: from the Workgroup of the Musculoskeletal Infection Society. Clin Orthop Relat Res. 2011;469:2992-2994. PMCID: PMC3183178. PMID: 21938532. DOI: 10.1007/s11999-011-2102-9.
- Hsieh PH, Shih CH, Chang YH, Lee MS, Shih HN, Yang WE. Two-stage revision hip arthroplasty for infection: comparison between the interim use of antibiotic-loaded cement beads and a spacer prosthesis. J Bone Joint Surg Am. 2004;86-A(9):1989-1997. PMID: 15342762.