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Hip Arthrodesis (Fusion)

Surgical technique guide for hip arthrodesis - a salvage fusion for the young, high-demand manual labourer with isolated end-stage unilateral hip arthritis: position of fusion, muscle-sparing technique, long-term adjacent-joint sequelae and conversion to total hip arthroplasty

Core Procedure
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High-yield overview

Salvage fusion for the young, high-demand manual labourer with isolated unilateral end-stage hip arthritis | advanced

Surgical Imaging

Critical Principles and Exam Traps

Position of Fusion — The Examined Triad

The trap: Reciting a vague "neutral" position. Examiners want the numbers: approximately 20 to 30 degrees of FLEXION, 0 to 5 degrees of ADDUCTION (neutral to slight), and 0 to 10 degrees of EXTERNAL ROTATION.

The fix: Flexion enables sitting and a level swing-through gait; neutral-to-slight adduction maintains a functional limb length; mild external rotation matches normal foot progression. Set and check this on the table before final fixation.

Never Fuse in Abduction

Why catastrophic: An abducted fusion functionally LENGTHENS the limb, forcing a Trendelenburg-type lurch, a perceived limb-length discrepancy and shoe raises, and markedly accelerated low-back and contralateral-hip overload.

The fix: Aim for NEUTRAL to SLIGHT ADDUCTION (0 to 5 degrees). Malposition — especially abduction — is among the most disabling and least forgivable technical errors in this operation.

Adjacent Joints Must Be Normal

The prerequisite: The ipsilateral KNEE, contralateral HIP and lumbar SPINE absorb the compensatory motion for the rest of the patient's life.

The fix: Degenerative change in any of these three is a RELATIVE contraindication; symptomatic disease there usually steers you toward arthroplasty instead. Examine and image them before consenting.

Bilateral Hip Disease

The rule: Bilateral end-stage hip arthritis is a CONTRAINDICATION to arthrodesis — you cannot fuse both hips and leave the patient able to sit, walk and perform perineal care.

The fix: Bilateral disease, inflammatory arthropathy (e.g. rheumatoid, ankylosing spondylitis) and any need for hip mobility favour arthroplasty, not fusion.

Preserve for Future Conversion

The principle: Most fused hips eventually come to conversion arthroplasty for adjacent-joint pain. Protect what the future THA will need.

The fix: Preserve the ABDUCTORS, the SUPERIOR GLUTEAL NERVE and the GLUTEAL VESSELS; favour muscle-sparing plate fixation over techniques that destroy the abductor mass. Abductor quality at conversion drives the eventual functional result.

Arthrodesis vs Arthroplasty Selection

Choose fusion: young, heavy manual labourer, isolated unilateral post-traumatic/post-infective arthritis, normal adjacent joints, willingness to accept a stiff hip for durability.

Choose arthroplasty: older or lower-demand patient, bilateral or inflammatory disease, adjacent-joint degeneration, need for hip motion. Modern THA longevity has made fusion rare, but the indication persists for the right young labourer.

Mnemonic

F.U.S.EFUSE POSITION — Position of Fusion

Mnemonic

S.E.L.E.C.TSELECT — Choosing the Right Patient for Hip Fusion

Rationale and Modern Role

Hip arthrodesis converts a painful, degenerate hip into a painless, stable, durable fused joint. It was historically a mainstay of treatment for end-stage hip disease in young adults before reliable arthroplasty existed. With modern total hip arthroplasty (THA) offering excellent pain relief and durability, hip arthrodesis is now a rare, salvage option — but it retains a defined niche and is high-yield as an examined principle.

The enduring logic: in a young, high-demand manual labourer, a well-positioned fusion will outlast any arthroplasty under heavy repetitive loading, with no bearing wear, no dislocation risk and no concern about implant longevity over a multi-decade working life.

Ideal Candidate

The Classic Indication

  • Young adult (commonly cited as under 30 to 40 years of age) with a long life expectancy and high physical demand
  • Heavy manual labourer for whom durability under load is paramount and arthroplasty longevity is genuinely doubtful
  • Isolated UNILATERAL end-stage arthritis of the hip
  • Most appropriate where the aetiology is post-traumatic (e.g. acetabular/femoral head fracture sequelae) or post-infective (sequelae of septic arthritis), often after trauma or infection that has already compromised the joint in a young person
  • Patient who understands and accepts a permanently stiff hip in exchange for a pain-free, dependable hip

Prerequisites (MUST be satisfied)

A successful fusion depends entirely on neighbouring joints absorbing the lost hip motion for life:

  • Normal ipsilateral KNEE — takes increased sagittal and rotational load
  • Normal contralateral HIP — compensates for lost motion and shares weight-bearing
  • Normal lumbar SPINE — compensates with increased lumbar motion (a frequent later pain source)

If any of these is already degenerate, the compensatory burden will be poorly tolerated and arthrodesis is contraindicated or strongly discouraged.

Contraindications

Absolute:

  • Bilateral hip disease — both hips cannot be fused (patient could not sit, manage stairs or perform perineal hygiene)
  • Active sepsis that cannot be eradicated before achieving fusion (though prior quiescent infection is actually a classic indication)
  • Inflammatory arthropathy (rheumatoid arthritis, ankylosing spondylitis) — disease is polyarticular and the adjacent joints will also be affected; spinal involvement is especially problematic

Relative:

  • Degenerative change in the ipsilateral knee, contralateral hip or lumbar spine — the load-sharing joints are already compromised
  • Older or lower-demand patient in whom arthroplasty durability is adequate
  • Patient unwilling to accept a stiff hip or the long-term sequelae

Arthrodesis versus Arthroplasty — The Selection Decision

Hip Arthrodesis versus Total Hip Arthroplasty — Patient Selection


Clinical Pearl

Examiner framing: 'I reserve hip arthrodesis for the young, high-demand manual labourer with isolated unilateral end-stage arthritis — typically post-traumatic or post-infective — who has a normal ipsilateral knee, a normal contralateral hip and a normal lumbar spine. I counsel them carefully that they are trading hip motion for durability, and that adjacent-joint pain is likely over the decades. In almost every other patient, modern total hip arthroplasty is now my preference.'


Clinical Decision Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOAdvanced

CLINICAL PROMPT

"A 28-year-old male labourer has end-stage post-traumatic arthritis of the right hip following an old acetabular fracture. He has severe pain and wants to keep working in heavy construction. His left hip, both knees and his lumbar spine are clinically and radiographically normal. He asks why you are discussing hip fusion rather than a replacement. How do you counsel him and how would you plan a fusion?"

PRACTICAL APPROACH
This young, high-demand manual labourer with isolated unilateral end-stage post-traumatic arthritis and entirely normal adjacent joints is the classic candidate for hip arthrodesis. **Why fusion is on the table**: In a 28-year-old doing heavy construction, the durability of any total hip replacement under repetitive high impact is a genuine concern over his likely 40-plus working years — he would face bearing wear, possible loosening and revision surgery, with activity restrictions in the meantime. A well-positioned fusion gives a painless, stable, durable hip that will tolerate heavy manual work indefinitely, with no implant to wear out. That trade-off — a permanently stiff hip in exchange for durability — is the central conversation. **Prerequisites I confirm**: His disease must be strictly unilateral, and his ipsilateral knee, contralateral hip and lumbar spine must be normal, because those joints will absorb the lost hip motion for the rest of his life. He satisfies all of these. **What I counsel him about**: That the hip will be permanently stiff; that I aim for a specific position — about 20 to 30 degrees of flexion, neutral to slight adduction (never abduction) and 0 to 10 degrees of external rotation — so he can sit and walk with a level gait; and crucially that over the coming decades he is likely to develop knee, low-back and opposite-hip pain from compensatory loading, which is the commonest reason patients later ask for a conversion to a replacement. **Operative plan**: Confirm no active infection, template the position, remove all articular cartilage from head and acetabulum to bleeding cancellous bone, set the limb at the target position checked against the other leg and with sitting/standing simulation, then achieve rigid internal fixation with interfragmentary compression (cobra-head or anterolateral plate with a lag screw across the joint). Throughout, I deliberately preserve the abductor mechanism, the superior gluteal nerve and the gluteal vessels so that a future conversion to arthroplasty is feasible and as successful as possible.
CLINICAL SCENARIOAdvanced

CLINICAL PROMPT

"In what position should the hip be fused, and why does position matter so much? What is the single error you must avoid?"

PRACTICAL APPROACH
Position is the most important determinant of outcome in a hip arthrodesis — a perfectly united but malpositioned fusion is a disabling result. **The target position**: Approximately 20 to 30 degrees of FLEXION, 0 to 5 degrees of ADDUCTION (neutral to slight), and 0 to 10 degrees of EXTERNAL ROTATION, with limb length matched to the contralateral side. **Why each plane matters**: - Flexion of 20 to 30 degrees lets the patient sit comfortably and gives a level, energy-efficient swing-through gait. Too little flexion (toward extension) makes sitting hard and forces compensatory lumbar motion; too much flexion exaggerates lumbar lordosis and worsens back pain. - Neutral-to-slight adduction keeps the limb a functional, level length. Slight external rotation matches the normal foot progression angle and eases the swing phase. **The single error to avoid is ABDUCTION**. Fusing in abduction functionally lengthens the limb, producing a perceived limb-length discrepancy, the need for shoe raises, a lurching Trendelenburg-type gait, and markedly accelerated low-back and contralateral-hip overload. It is among the most disabling and least forgivable technical errors in this operation. If I am ever in doubt, I err toward neutral or a few degrees of adduction — never abduction. **Practically**: I provisionally fix the position, then re-check it against the contralateral limb and simulate both sitting and standing on the table before applying compression — and I confirm the final position again afterward, because compression can shift the limb.
CLINICAL SCENARIOAdvanced

CLINICAL PROMPT

"A 50-year-old man had a hip fusion 22 years ago for post-traumatic arthritis. The fusion is solid but he now has intractable low-back pain and ipsilateral knee pain. He wants 'to be able to move the hip again'. What is going on, what do you offer, and how does conversion differ from a primary hip replacement?"

PRACTICAL APPROACH
This is the typical long-term evolution of a hip fusion. The fusion itself is intact; his symptoms come from the ADJACENT JOINTS that have been overloaded and made hypermobile for two decades to compensate for the absent hip motion — producing low-back pain and ipsilateral knee pain. This adjacent-joint degeneration is the commonest reason fused patients return seeking conversion. **What I offer**: Conversion of the fused hip to a total hip arthroplasty. Restoring hip motion characteristically relieves the compensatory back and knee pain, which is usually his main complaint, and gives him a mobile hip again. **How conversion differs from a primary THA**: I counsel him that this is a bigger, technically more demanding operation with a less predictable outcome than a primary replacement: - The key variable is his ABDUCTOR function. After 22 years of fusion the abductors are likely weak or scarred, and abductor strength is what determines gait and function afterward — a limp or Trendelenburg gait is common. - I may need a TROCHANTERIC OSTEOTOMY to access the joint and to mobilise and reattach the abductors, which adds the risk of osteotomy nonunion and hardware problems. - The anatomy is distorted, there may be retained hardware and heterotopic bone, and the soft-tissue envelope is contracted — all increasing complexity. - Pain relief, especially of the back and knee, is generally good, but functional outcomes and complication rates are less predictable than primary THA. **Assessment before surgery**: I document abductor status as far as possible, image the bone stock and any retained hardware, and confirm there is no occult infection (especially as his original problem was post-traumatic). I set realistic expectations: the back and knee pain should improve, but he may walk with a limp.

Hip Arthrodesis (Fusion) — Exam Day Summary

Clinical summary

Key Evidence

Hip arthrodesis: a long-term follow-up

Level IV
Callaghan JJ, Brand RA, Pedersen DR • J Bone Joint Surg Am
Clinical Implication: The landmark study cementing two exam points: adjacent-joint (knee, back, contralateral hip) degeneration emerges progressively over decades, and fusing in abduction directly worsens it — so aim for neutral-to-slight adduction, never abduction.
Verify on PubMed (PMID 4077903)

Hip arthrodesis in young patients: a long-term follow-up study

Level IV
Sponseller PD, McBeath AA, Perpich M • J Bone Joint Surg Am
Clinical Implication: Validates the core indication: a well-positioned fusion in a young patient is durable enough to sustain a full working life, with most never needing conversion — though adjacent-joint symptoms are common with very long follow-up.
Verify on PubMed (PMID 6234319)

Hip arthrodesis: current indications and techniques

Level V
Beaule PE, Matta JM, Mast JW • J Am Acad Orthop Surg
Clinical Implication: The modern reference for the examined position triad, the over-80-percent fusion rate, and the logic of conversion — including the determinants of a good conversion result.
Verify on PubMed (PMID 15089074)

Hip arthrodesis: a procedure for the new millennium?

Level V
Stover MD, Beaule PE, Matta JM, Mast JW • Clin Orthop Relat Res
Clinical Implication: Frames the contemporary, narrowed indication (young, monoarticular, non-inflammatory) and the principle of abductor-sparing technique to safeguard a future conversion.
Verify on PubMed (PMID 15043103)

Total hip arthroplasty in the ankylosed hip: a ten-year follow-up

Level IV
Strathy GM, Fitzgerald RH • J Bone Joint Surg Am
Clinical Implication: Quantifies why conversion of a surgically fused hip is less predictable than primary THA — prior surgery and younger age at conversion both raise failure risk, reinforcing careful patient counselling.
Verify on PubMed (PMID 3403586)

References

  1. Callaghan JJ, Brand RA, Pedersen DR (1985). Hip arthrodesis. A long-term follow-up. J Bone Joint Surg Am 67(9):1328-35. PMID 4077903. — Long-term follow-up demonstrating durable pain relief but progressive ipsilateral knee, low-back and contralateral-hip symptoms over decades, and worse adjacent-joint pain when fused in abduction.

  2. Sponseller PD, McBeath AA, Perpich M (1984). Hip arthrodesis in young patients. A long-term follow-up study. J Bone Joint Surg Am 66(6):853-9. PMID 6234319. — Outcomes in patients fused before age 35 (mean 38-year follow-up); supports durability for high-demand use and documents adjacent-joint sequelae.

  3. Stover MD, Beaulé PE, Matta JM, Mast JW (2004). Hip arthrodesis: a procedure for the new millennium? Clin Orthop Relat Res 418:126-33. PMID 15043103. — Reviews the contemporary, narrowed indication for fusion in the young monoarticular non-inflammatory patient and the principle of abductor-sparing technique.

  4. Beaulé PE, Matta JM, Mast JW (2002). Hip arthrodesis: current indications and techniques. J Am Acad Orthop Surg 10(4):249-58. PMID 15089074. — Summarises modern indications, the optimal position of fusion, the over-80-percent fusion rate with current fixation, and the logic of conversion.

  5. Strathy GM, Fitzgerald RH (1988). Total hip arthroplasty in the ankylosed hip. A ten-year follow-up. J Bone Joint Surg Am 70(7):963-6. PMID 3403586. — Conversion of fused/ankylosed hips to arthroplasty; surgically fused hips carried a 33 percent complication rate and failure was more likely after prior surgical arthrodesis and in younger patients.

  6. Hardinge K, Murphy JC, Frenyo S (1986). Conversion of hip fusion to Charnley low-friction arthroplasty. Clin Orthop Relat Res 211:173-9. PMID 3769258. — Classic series on converting hip fusion to THA; advocates trochanteric osteotomy with the patient supine for adequate exposure and abductor reattachment.