What all four approaches share — and where they differ

The surgical approach matters — but perhaps not in the way most patients expect. Whether a surgeon operates from the front, back, or side of the hip, the procedure itself is the same: the damaged femoral head is removed and replaced with a prosthetic ball, and the acetabulum is resurfaced with a new socket. The implants used across all four approaches are identical, and approximately 58% of hip replacements are estimated to last 25 years regardless of which route was taken to fit them. Published evidence, including a comparative study of 62 patients, has found no significant difference in all-cause revision rates between approaches over the long term.

Where the approaches diverge — and diverge meaningfully — is in what happens during the operation and in the weeks that follow. Each of the four main techniques accesses the hip joint from a different anatomical direction, which determines which muscles, tendons, or capsular structures must be cut, temporarily displaced, or left intact. Those differences shape the early recovery experience, the specific complications that carry the highest risk, and the postoperative restrictions a patient must observe.

The four approaches are:

• Direct Anterior Approach (DAA) — an incision at the front of the hip, working between muscle planes without cutting into them
• Traditional Posterior Approach — entry from behind the hip, releasing the short external rotator tendons to access the joint
• Lateral (Hardinge) Approach — a side incision involving the gluteus medius, the primary hip abductor muscle
• SPAIRE — a modified posterolateral technique that preserves the piriformis and obturator internus tendons throughout, first described by Kim et al. in 2008

No single approach is universally superior. The right choice depends on individual anatomy, the operating surgeon's expertise, and what matters most to the patient during recovery. The sections that follow compare each technique on exactly those terms.

Direct Anterior Approach — faster early recovery, specific nerve risk

For patients whose priority is getting back on their feet quickly, the direct anterior approach has a genuine evidence-based claim. Because the incision runs through a natural interval between muscle planes at the front of the hip — rather than through or around any muscle belly — the surrounding tissues suffer less disruption. In a comparative study of 62 patients, those who received the DAA reported significantly less pain at one and three months postoperatively, needed mobility aids for a shorter period, and achieved superior Harris Hip Scores at six and twelve weeks compared with those treated via the traditional posterior approach. For someone with demanding domestic or professional commitments, that earlier functional window can matter considerably.

The DAA's complication profile, however, carries one risk that deserves clear explanation before any patient commits to it. The lateral femoral cutaneous nerve (LFCN) runs directly through the anterior corridor the surgeon must work within. Traction on this nerve during the procedure — even when carefully managed — can cause neurapraxia: a patch of numbness or tingling across the outer thigh, sometimes described as a band of altered sensation roughly the size of a hand. In some patients this resolves over weeks or months; in others it may be permanent. This is not a rare catastrophic complication but a recognised, pathway-specific risk that does not occur with posterior or SPAIRE approaches.

Beyond nerve injury, the DAA tends to involve longer operating times and greater intraoperative blood loss than the posterior approach. There is also a documented learning curve: surgeons still acquiring familiarity with the technique carry a higher rate of intraoperative femur fractures during femoral canal preparation — a complication that adds operative complexity and recovery time. These factors are primarily relevant to how surgeons select candidates and set up theatre, but patients are entitled to understand them.

The important counterbalance is that none of the DAA's early advantages appears to translate into better long-term outcomes. All-cause implant revision rates are equivalent between the DAA and the posterior approach. The choice here is about what a patient is willing to trade — a faster early recovery against a meaningful, sometimes permanent, nerve risk — not about which approach will last longer.

Posterior approach — the most widely performed technique

Globally, more hip replacements are performed via the posterior approach than by any other technique. That prevalence is itself meaningful: surgeons have accumulated decades of experience with it, its complication profile is extensively documented, and theatre teams worldwide are practised in its execution. For patients, this translates into a widely available procedure with a well-understood risk pattern.

From an operative standpoint, the posterior approach compares favourably with the DAA on several measures — it is generally faster to perform, offers broader anatomical exposure of the acetabulum and proximal femur, and produces less intraoperative blood loss. These characteristics make it technically versatile and readily extensible if the surgeon encounters unexpected anatomy.

The central patient concern, however, is dislocation risk. To reach the hip joint from behind, the surgeon must release the short external rotator tendons — the same structures that, in an intact hip, provide an important mechanical check against the femoral head slipping backwards out of the socket. Once cut, these tendons need time to heal and regain functional tension. During this window, which broadly aligns with the first six to twelve weeks, the joint is more vulnerable than it would normally be.

The consequences of dislocation, when it occurs, are significant. Evidence shows that 57% of patients who experience one dislocation will go on to experience more than one; 11% will sustain five or more events; and 45.6% will require complex revision surgery within two years. Modern capsular repair techniques have reduced dislocation rates compared with older posterior methods, though the repair does not fully restore native tissue integrity immediately.

To manage that vulnerability, traditional posterior approach protocols typically impose strict movement restrictions for up to 90 days: no hip flexion beyond 90 degrees, no internal rotation, and no adduction across the midline. These precautions are effective, but they carry a real cost. Bending to put on socks, rising from low chairs, and using a standard toilet all require modification. For patients living alone or returning to a physically active life, this restriction period imposes a meaningful constraint on early independence.

Lateral approach — abductor risk and declining use

Considerably less common at specialist hip centres than either of the approaches described above, the lateral — or Hardinge — approach accesses the joint from the side of the hip. To create the necessary window, the surgeon must split or partially detach the gluteus medius, one of the primary muscles responsible for stabilising the pelvis during walking.

That anatomical requirement is what defines the approach's main patient-relevant risk. When healing of the gluteus medius is incomplete, the muscle may not regain its full stabilising force. The practical result is a Trendelenburg gait: with each step on the operated leg, the pelvis drops visibly towards the opposite side rather than staying level. In mild cases this produces a subtle limp; in more pronounced cases it is conspicuous and tiring. The weakness can persist for months, and in a proportion of patients it does not fully resolve.

Major specialist centres, including Hospital for Special Surgery in the United States, now perform the lateral approach infrequently in routine primary hip replacement. It retains a role in certain revision contexts or where specific anatomical considerations make other approaches less practical.

The evidence base for the lateral approach is notably thinner than for the DAA or posterior technique — the risk descriptions above draw largely on anatomical reasoning and centre-level usage patterns rather than large controlled trials. Patients considering this approach, or being counselled about it, should be aware of that limitation when weighing comparative claims.

SPAIRE — a muscle-sparing posterior approach and how it differs

SPAIRE works differently from a posterior approach that simply repairs what was cut. Rather than detaching and reattaching the piriformis and obturator internus tendons, it leaves them intact throughout.

The strap effect

The obturator internus tendon exits the pelvis and passes directly over the posterior femoral head, close to its centre of rotation. Left undisturbed, it acts like a seatbelt across the back of the joint — held under continuous tension by the muscle behind it, pressing the femoral head into the socket and resisting the pull that causes posterior dislocation. This 'strap effect' is active from the moment surgery ends, not from the point when cut tissue eventually heals.

Proprioceptive continuity

The second mechanism is neurological. Golgi tendon organs and muscle spindles embedded within the intact short external rotators continuously feed positional information to the central nervous system. When the standard posterior approach severs these structures, the hip loses real-time feedback until nerve regeneration occurs. SPAIRE preserves it immediately — the joint's reflexive protection against subluxation is functioning rather than absent in the critical early days after surgery.

Together, these mechanisms are associated with lower dislocation rates and a reduced need for strict postoperative movement precautions.

Robotic assistance and the visual trade-off

Preserving the posterior soft tissues narrows the surgeon's visual field compared with a standard posterior exposure. Mako robotic-arm assistance compensates directly: it provides sub-millimetre precision for bone resection and implant positioning without requiring the wider opening a standard approach offers. Retaining native soft-tissue tension also gives the surgeon direct tactile feedback for judging leg length and femoral offset intraoperatively.

Suitability and evidence

Not every candidate for posterior hip replacement will be suitable for SPAIRE. Individual anatomy — reviewed on imaging before surgery — determines whether the technique is appropriate. That decision is reached at a specialist consultation, not on the basis of patient preference alone.

The mechanistic rationale for SPAIRE is well-supported, and case-series data indicate lower dislocation rates in suitable patients compared with the traditional posterior approach — a meaningful difference given the outcomes described when posterior dislocation does occur. Large randomised controlled trials directly comparing SPAIRE with the DAA or standard posterior technique remain limited in the published literature. That is an honest gap in the evidence rather than a reason to dismiss the technique, but it is one a specialist assessment should address in the context of an individual's anatomy and surgical history.

How surgeons and patients decide together

Four approaches, one joint, no universal answer — which technique is most appropriate emerges from a structured conversation that considers each patient's anatomy, bone quality, BMI, prior surgery, and what they most need from the weeks immediately after the operation.

The principal trade-off axes worth raising before any decision is finalised:

• DAA versus nerve risk: faster early function, superior Harris Hip Scores at six and twelve weeks, but LFCN neurapraxia — including the possibility of permanent lateral thigh numbness — is a pathway-specific risk that does not affect posterior or SPAIRE approaches
• Traditional posterior approach versus restriction burden: broadly applicable and technically versatile, but the 90-day precaution window carries a genuine cost to independence, and dislocation when it occurs has serious downstream consequences
• Lateral approach: a role in specific anatomical contexts, but gluteus medius disruption and Trendelenburg gait affect day-to-day walking and should be weighed accordingly
• SPAIRE versus candidacy limits: mechanistically sound rationale for lower dislocation risk and reduced precautions, but anatomical suitability is determined on imaging — not every patient who wants to avoid hip precautions will qualify

Surgeon volume and familiarity with the recommended technique are legitimate factors. Complication rates — particularly for the DAA, where the learning curve is steepest — are meaningfully associated with a surgeon's experience. Patients should feel able to raise this directly in consultation.

Determining approach suitability requires imaging review and an unhurried clinical conversation that covers each technique's specific complication profile, not just headline recovery times. Hip Replacement Lincolnshire, part of the MSK Doctors group, accepts patients without GP referral for consultant-led assessment; further information is at hipreplacementlincolnshire.co.uk.