Does the surgical approach to hip replacement actually matter?

The route a surgeon takes to reach the hip joint matters more than many patients expect. All four main approaches — anterolateral (Watson-Jones), standard posterior, direct anterior (DAA), and SPAIRE (a muscle-sparing modification of the posterior route) — replace the same worn joint with the same implant. What differs is which muscles and tendons are moved or cut to get there, and those differences carry real consequences: how quickly someone walks without a limp, how low the dislocation risk is, and what movement rules apply in the weeks after surgery.

A large prospective study of 1,089 hip replacements found that five-year functional scores, dislocation rates, and revision rates were broadly equivalent between the anterolateral and posterior approaches — so the long-term destination is similar across techniques. The meaningful variation lies in the journey: early recovery speed, gait quality, and rehabilitation restrictions can differ substantially depending on which tissue plane the surgeon uses.

No single approach suits every patient. Surgeon training, patient build, bone anatomy, and individual dislocation risk all feed into the decision. The sections below work through each approach in turn.

The anterolateral approach: what it protects and where its risks lie

Two terms that appear interchangeably in patient information — 'anterolateral' and 'direct lateral' — describe meaningfully different operations, and the distinction has real consequences for walking gait after surgery.

The true anterolateral, or Watson-Jones, approach reaches the hip through the natural gap between two muscles: the tensor fasciae latae (at the front) and the gluteus medius (at the side). Because the surgeon works between these muscles rather than through them, and leaves the posterior joint capsule untouched, the hip is inherently stable against posterior dislocation. Post-operative restrictions for this route reflect the direction of remaining risk: patients are asked to avoid hip extension, extreme external rotation, and bringing the leg across the midline — a different set of rules from the posterior approach's flexion-based restrictions.

The direct lateral (Hardinge) approach, by contrast, detaches and then re-anchors the gluteus medius from the greater trochanter. That reattachment is the source of a substantially higher risk of Trendelenburg gait — the characteristic dip of the pelvis that produces a noticeable limp. A randomised controlled trial of 150 hemiarthroplasty patients (Ugland 2019) found that one in five treated via the direct lateral approach had a positive Trendelenburg test at 12 months, against fewer than two in a hundred with the true anterolateral (RR 11.1; p = 0.004). Those with a positive Trendelenburg test also recorded significantly worse hip scores, confirming that this is a clinically meaningful gap — not a technical footnote.

Patient-facing literature rarely flags this distinction, so it is worth raising explicitly in any conversation about approach selection.

The posterior approach: dislocation trade-offs and evolving repair techniques

The posterior approach accesses the hip by splitting gluteus maximus — the large buttock muscle — and cutting through the short external rotators at the back of the joint: the piriformis, obturator internus, and gemelli tendons. These tendons are repaired at the end of the operation, but their temporary division is the anatomical origin of the approach's historically elevated dislocation risk. Published dislocation rates across posterior-approach series range from 0.2% to 10%, a wide spread that reflects differences in surgical technique and the rigour of soft-tissue closure.

The traditional response to that risk was strict post-operative precautions: no hip flexion beyond 90°, no adduction across the midline, and no internal rotation — maintained for six to twelve weeks. A systematic review of seven studies covering 6,900 patients (Crompton 2020) found, however, that dislocation rates were 2.2% with precautions and 2.0% without them — a statistically non-significant difference, with no measurable effect on patient-reported outcomes. The implication is that meticulous repair of the posterior capsule and rotator tendons does more to prevent dislocation than any set of movement restrictions imposed afterwards.

This reframing carries practical weight. The 1,089-patient, five-year trial (Palan 2008) established that a well-executed posterior approach produces equivalent Oxford hip scores, dislocation rates, and revision rates to the anterolateral over the long term — a finding that holds when repair technique is sound. The posterior route remains the most widely performed hip replacement approach in the UK, meaning most surgeons are trained in it and a large body of comparative outcome data supports its use. It is also the foundation on which SPAIRE, the muscle-sparing modification covered in the next section, was built.

SPAIRE hip replacement: what the muscle-sparing posterior approach changes

SPAIRE does one thing differently from every other posterior technique: it leaves two of the three short external rotators — the piriformis and obturator internus — completely intact. Only the obturator externus is detached and then repaired. Because the piriformis and obturator internus together form the posterior soft-tissue sling that prevents the new femoral head from slipping backwards, their preservation maintains natural joint restraint from the moment the wound is closed. The standard posterior approach sacrifices all three tendons and relies on meticulous repair to recreate what SPAIRE simply never disturbs.

The clinical consequences are measurable. Published dislocation rates for SPAIRE combined with the Exeter cemented femoral stem are approximately 0.4–1.0% — among the lowest reported for any approach. Because the posterior restraint is intact, many surgical teams do not impose strict post-operative hip flexion restrictions, removing the 'no bending past 90°' rule that has historically shaped posterior-approach rehabilitation.

Functional outcomes appear to follow suit. A 2025 comparative study (Paus) found that SPAIRE patients achieved significantly better scores on the New Mobility Scale, Short Physical Performance Battery, and walking speed than patients treated via the direct lateral approach, with no difference in dislocation, infection, or mortality rates. A UK series of 35 patients (Kumar 2024) reported 65% good-to-excellent functional outcomes and zero complications at short-term follow-up.

Most published SPAIRE data currently originate from specialist centres, and long-term comparative data against other muscle-preserving techniques are still accumulating. Individual anatomy, body habitus, and surgical risk profile determine whether the approach is appropriate for a given patient — the kind of assessment that informs consultant-led decision-making at centres such as Lincolnshire Hip, where Prof Paul Lee's surgical practice encompasses SPAIRE alongside other approaches. A registered UK trial (ISRCTN27974201) comparing SPAIRE directly with the Posterior Soft-tissue Preserving Approach — Exeter Hip Unit's established technique — will add important comparative evidence in a routine NHS population.

The direct anterior approach: early recovery gains and surgical demands

Running between two muscle groups — tensor fasciae latae on the outer side and sartorius and rectus femoris on the inner — the direct anterior approach (DAA) reaches the hip joint without cutting or detaching any muscle. The incision passes through a natural anatomical interval, and it is this arrangement that underlies the approach's well-documented early recovery advantage: muscles left structurally intact resume function sooner than muscles that have been divided and repaired.

A further practical benefit is intraoperative fluoroscopy. Because the patient lies supine on a specialised table, the surgeon can take real-time X-ray images during the procedure to verify cup angle, leg length, and implant position before closing — a level of intraoperative feedback that the posterolateral and anterolateral positions make harder to achieve.

These advantages carry recognised trade-offs. The DAA has a steep surgical learning curve; published evidence suggests that complication rates, particularly wound problems, are meaningfully higher during a surgeon's early case volume. In obese or heavily muscular patients the natural interval narrows, making instrument handling technically demanding. The lateral femoral cutaneous nerve — a purely sensory nerve that crosses the surgical field — is at particular risk: numbness or dysaesthesia over the front of the thigh is a recognised and usually temporary complication, though it persists in some patients.

The approach also limits intraoperative access to the abductor tendons (gluteus medius and minimus). Where coexisting abductor pathology is suspected, both the anterolateral and posterior routes offer easier inspection and repair — an anatomical constraint that is relevant to patient selection.

Which approach suits which patient — and what to ask

Choosing between these techniques comes down to matching each patient's clinical profile and priorities to what the approaches actually do differently — not to which one sounds most modern.

A few factors consistently shift the recommendation:

• Minimising post-operative movement restrictions — both SPAIRE and the direct anterior approach typically remove the 'no bending past 90°' rule because neither disrupts the posterior restraint that makes the restriction necessary; the anterolateral and standard posterior approaches impose different but real movement limits during healing.
• Walking gait concern — the true anterolateral (Watson-Jones) carries substantially less Trendelenburg limp risk than the direct lateral (Hardinge) variant; patients for whom this is a specific concern should confirm which of the two their surgeon actually performs.
• Earliest independent recovery — the direct anterior approach suits this goal, provided surgical case volume is sufficient and the patient's anatomy makes the intermuscular interval accessible.
• Lowest dislocation risk — SPAIRE's preserved posterior sling addresses this directly, particularly for patients whose daily activities or lifestyle involve wide hip movement.
• Breadth of long-term evidence — the anterolateral approach carries a large outcomes dataset; a prospective study of more than 1,000 arthroplasties found equivalent hip scores, dislocation, and revision rates against the posterior approach at five years, confirming it as a well-evidenced choice rather than a compromise.

Across all four approaches, long-term functional outcomes tend to converge. The meaningful differences are concentrated in the early-recovery pathway and in the specific soft-tissue trade-offs each route makes — precisely the considerations that individual anatomy, body habitus, and surgical experience are needed to weigh.

Questions worth raising at consultation

• Which approach do you routinely perform, and what is your personal dislocation rate with it?
• Will I need hip precautions, and for how long?
• Does my weight, anatomy, or hip pathology make any approach less suitable?
• If minimising restrictions matters to me, is SPAIRE or the direct anterior approach appropriate in my case?

Lincolnshire Hip is part of the MSK Doctors group and accepts patients without referral for hip assessment, with clinics in Sleaford and Grantham. Consultant-led evaluation — drawing on Prof Paul Lee's surgical experience across muscle-sparing posterior approaches including SPAIRE hip replacement — is the appropriate way to identify which route fits a specific patient's anatomy, risk profile, and recovery priorities.

1. [1] The Modified SPAIRE Approach for Hip Arthroplasty (Cureus 2023). (2023). https://doi.org/10.7759/cureus.34999 https://doi.org/10.7759/cureus.34999
2. [2] Details of a Tendon-Sparing Posterior Approach in Hemiarthroplasty (SPAIRE technique, 2017). (2017). https://doi.org/10.4172/2167-7921.1000243 https://doi.org/10.4172/2167-7921.1000243