Which hip replacement approaches matter most

Hip replacement reaches the same hip joint through different routes, and those routes matter because they pass through different muscles, tendons, capsule tissue and nearby nerves. The main comparison here is SPAIRE hip replacement, standard posterior, lateral and anterior approaches.

SPAIRE hip replacement is a muscle-sparing posterior approach: in plain language, it aims to preserve the short external rotators and other soft tissues around the hip joint where possible, rather than dividing them in the usual way. That makes it a practical variation of posterior surgery, not a separate operation on a different joint.

No single approach is best for everyone. Patient suitability, hip anatomy, the diagnosis, implant choice and the surgeon’s experience all shape the decision, and Prof Paul Lee’s clinical explanation of SPAIRE follows that same surgeon-led, case-by-case logic. The two issues that matter most to most people are dislocation risk and nerve symptoms after hip replacement, because those are the complications most clearly tied to approach choice.

How dislocation risk differs by approach

Dislocation risk after hip replacement is shaped by more than the chosen route into the hip joint. Component position, soft-tissue repair, implant design, head size, dual-mobility use and patient factors all contribute, so no approach can be judged in isolation.

The clearest comparative signal in the current evidence is about pattern, not a simple ranking. In a 2023 study of primary total hip arthroplasty, the posterior approach had a lower rate of anterior dislocation, while nearly 60% of direct anterior approach dislocations occurred posteriorly. That matters because it shows that different approaches may fail in different directions, rather than one route being uniformly safer in every case.

Modern posterior hip replacement should not be treated as automatically high risk. Contemporary technique and implant choices can lower instability substantially; one 2023 series using a mini-posterior approach with a dual-mobility construct reported just 1 dislocation in 580 hips, or 0.2%. In other words, the skin incision or corridor matters less than the way the hip joint is reconstructed and stabilised.

Where SPAIRE fits

SPAIRE hip replacement is a muscle-sparing posterior approach designed to preserve stabilising structures around the hip joint. By keeping more of the posterior soft tissue intact, it is intended to support stability and may reduce dislocation risk, which is why it is often discussed as a muscle-sparing posterior approach rather than a separate category of surgery.

The balance of evidence is still limited, especially for primary total hip replacement. A 2025 systematic review of hemiarthroplasty studies suggested SPAIRE may improve early mobility and pain, with broadly comparable long-term outcomes, and a 2023 series reported no SPAIRE dislocations versus 2 in anterolateral cases and 2 in posterior cases. Those findings are promising, but they do not yet prove clear superiority across all hip replacement settings.

What is less certain

Evidence for the lateral approach is thinner in the current retrieval, so it is safer not to claim a precise place for it on absolute dislocation risk. The most defensible summary is that approach influences instability, but the size of that effect depends on patient suitability, implant choice, soft-tissue handling and surgeon technique — the same factors a specialist such as Prof Paul Lee would weigh when discussing SPAIRE hip replacement in practice.

What nerve symptoms can happen after hip replacement

After hip replacement, nerve symptoms can range from a small numb patch to a more obvious motor problem. Common complaints include tingling, burning, altered skin sensitivity, numbness, weakness, and, in more serious cases, foot drop. The key point is that these symptoms come from the nerves around the hip joint being stretched, pressed, irritated, or rarely injured during the operation, not from the replacement joint itself.

The direct anterior approach is the one most closely linked with lateral thigh numbness or tingling, usually affecting the lateral femoral cutaneous nerve. That nerve is a sensory nerve, so the symptom is typically a patch of altered feeling on the outer thigh rather than loss of strength. The symptom is often described as neurapraxia, which means the nerve has been temporarily stunned rather than cut.

Many sensory symptoms improve with time, but recovery is not identical for every nerve. The published review on nerve injury after total hip arthroplasty reports an incidence of about 0.6% to 3.7%, with outcomes varying according to the nerve involved and the severity of the injury. Femoral nerve palsy tends to recover more predictably than sciatic nerve palsy, but even then the course can be incomplete and slow.

Symptoms that need prompt review

• Progressive weakness after the operation, especially if it is getting worse from one day to the next
• New foot drop, or trouble lifting the front of the foot
• Severe or escalating pain, rather than the expected post-operative soreness
• Worsening numbness, spreading loss of sensation, or marked foot or thigh symptoms
• Symptoms that do not fit the usual early recovery pattern

These red flags matter because some causes are compressive and time-sensitive, such as a haematoma. Severe, progressive, or unexplained nerve symptoms after hip replacement warrant urgent assessment rather than routine follow-up. In practice, that is the point at which surgeon-led review matters most, including after a muscle-sparing posterior operation such as SPAIRE hip replacement when the symptom pattern is not typical for the expected recovery.

For most people, the practical distinction is between temporary sensory change and true loss of function. A numb outer thigh after an anterior approach may settle gradually, whereas new weakness, foot drop, or worsening pain needs faster attention because it suggests more than simple irritation around the hip joint.

How SPAIRE compares with posterior lateral and anterior

SPAIRE hip replacement is best understood as one option within a broader set of hip joint approaches, not as a universal default. In specialist practice, Prof Paul Lee’s clinical perspective frames it as a muscle-sparing posterior approach: it keeps more of the posterior stabilisers intact than a conventional posterior route, which may suit some patients where preserving those tissues is a priority.

Compared with a standard posterior approach, the main difference is tissue handling. SPAIRE aims to spare piriformis and obturator internus, and to repair the short external rotators rather than dividing them more widely. That may help early stability and mobilisation, but it still remains a posterior corridor into the same hip joint, so it does not remove every posterior-approach consideration.

The comparison with a lateral approach is less certain from the current evidence. A lateral route uses a different path to the hip and has different soft-tissue trade-offs, but the retrieved material does not give a strong head-to-head dataset that quantifies exactly how it compares with SPAIRE for dislocation or nerve injury in primary hip replacement. That makes cautious wording important: the practical differences are real, but the size of those differences is not yet well pinned down here.

Against a direct anterior approach, the trade-off is clearer. Anterior surgery avoids splitting posterior tissues, but it sits closer to the lateral femoral cutaneous nerve territory, so lateral thigh numbness or tingling is a more approach-relevant symptom. SPAIRE, by contrast, keeps the discussion centred on posterior soft-tissue preservation rather than anterior cutaneous nerve symptoms.

SuperPATH is worth mentioning as another tissue-preserving concept, because it shows SPAIRE is part of a wider movement towards less disruptive hip arthroplasty, not an isolated idea. Even so, patient suitability still decides the route: anatomy, fracture versus arthritis, previous surgery, body habitus, implant requirements, and surgeon familiarity can all make SPAIRE more or less appropriate for a particular hip joint.

In practice, that means SPAIRE hip replacement is a balanced option for selected patients, not a blanket replacement for posterior, lateral, or anterior surgery. The question is usually which approach gives the safest, most reliable access to the hip for that person and that operation, rather than which name sounds least invasive.

When symptoms are normal and when to seek review

What counts as expected recovery

In the first days and weeks after hip replacement, some soreness, bruising, stiffness and limited confidence in the hip joint are common. A small area of numbness near the scar can also be part of routine healing, particularly when the skin and soft tissues are still settling after surgery. These symptoms usually improve gradually rather than all at once.

Signs that need prompt assessment

A sudden change is more concerning than steady soreness. Prompt review is warranted if there is:

• a visible deformity, or the leg looks rotated or shorter than expected
• severe new pain after a movement, twist or fall
• an inability to bear weight on the operated side
• a strong sense that the hip has shifted, slipped, or come out of place

Those features raise concern for dislocation or another mechanical problem around the hip joint, and they need specialist assessment rather than simple reassurance.

When nerve symptoms should not be ignored

Worsening weakness, a new foot drop, escalating burning pain, or a spreading loss of sensation also deserve prompt review. The same applies when symptoms are getting worse instead of easing over several days, or when numbness is accompanied by clear loss of function. The published review on nerve injury after total hip arthroplasty notes that compressive causes such as haematoma may need timely assessment.

Why self-diagnosis is unreliable

Internet descriptions can make approach-specific problems sound much tidier than they are in real life. Swelling, bruising, muscle spasm and routine post-operative pain can overlap with symptoms that also occur after dislocation or nerve irritation. For that reason, the surgical approach by itself is not enough to explain a new symptom pattern after hip replacement, including after SPAIRE hip replacement, which is a muscle-sparing posterior approach.

Specialist review should consider the timing after surgery, the implant used, the examination findings, and the approach chosen. That kind of surgeon-led assessment is the clearest way to tell normal healing from a problem that needs action.

1. [1] Rethinking Hip Surgery: A Systematic Review of Sparing Piriformis and Internus, Repairing Externus (SPAIRE) vs. Traditional Hemiarthroplasty Approaches. (2025). https://doi.org/10.7759/cureus.89115 https://doi.org/10.7759/cureus.89115