Two routes to the same hip joint

When a surgeon mentions choosing between approaches for hip replacement, the question can feel unexpectedly technical. Put simply, both the lateral (Hardinge) approach and the SPAIRE technique are established surgical routes to the same hip joint — but they reach it from different directions, and they treat the surrounding soft tissues very differently.

The lateral approach has been a widely used standard for decades and remains NICE-referenced for hip surgery in the UK. The surgeon enters from the side of the hip, splitting or partially detaching the front portion of the gluteus medius and minimus — the abductor muscles that help stabilise the pelvis during walking. SPAIRE, by contrast, was first described in 2016 at the Exeter Hip Unit and belongs to the posterior family of approaches. Its defining feature is that it divides only one tendon — the obturator externus — and repairs it at the end of the procedure, leaving the piriformis and obturator internus tendons completely intact.

That difference in tissue handling drives most of the practical distinctions between the two: recovery restrictions, early pain, gait, and dislocation risk. Neither approach is the right choice for every patient — surgeon expertise, individual anatomy, and clinical context all shape the decision. The sections that follow compare both approaches across the factors that matter most to patients weighing their options.

What each approach does to the surrounding muscles

The key anatomical difference plays out in what each approach must displace to reach the hip socket.

For the lateral (Hardinge/transgluteal) approach, gaining access requires splitting or partially detaching the anterior third of the gluteus medius and minimus — the muscles that level the pelvis with each step. The anterior branch of the superior gluteal nerve runs approximately 3–5 cm above the greater trochanter within this tissue, and retraction during the exposure places it at risk. Where nerve function is affected, patients may develop a Trendelenburg gait — a characteristic dip towards the operated side when weight-bearing — which in some cases proves prolonged or permanent. Fatty atrophy of the gluteus medius has also been documented in a proportion of patients after lateral-approach surgery. To protect the repaired muscle while it heals, most centres impose 4–6 weeks of postoperative abduction restrictions.

SPAIRE enters the same joint through the posterior interval but takes a deliberately selective path through the soft tissue. Rather than repeating the mechanism covered in the previous section, it is worth focusing on the functional consequence: because the piriformis and obturator internus remain intact, the hip retains its posterior restraint from day one. That continuity is the proposed anatomical basis for why standard hip precautions can typically be lifted for SPAIRE patients — something that is not possible after approaches that detach and repair these structures. Professor Timperley at the Exeter Hip Unit, where the technique was developed, has performed SPAIRE in over 1,026 routine primary hip replacements, providing the case volume needed to characterise its soft-tissue behaviour across a wide range of patients.

What the evidence shows so far

Three published datasets now offer direct comparisons, with a fourth under way.

The most actionable comes from Paus et al. (2025), a comparative study published in PubMed (PMID 40279802). Patients who received hip replacement via the SPAIRE approach achieved better scores on the New Mobility Score, the Short Physical Performance Battery, and walking speed than those treated via the direct lateral approach. Crucially, the same study found no statistically significant difference between the two groups in prosthesis dislocation, deep infection, or mortality. That combination — superior functional recovery alongside an equivalent safety profile — represents the strongest head-to-head signal currently in the literature.

The HemiSPAIRE multicentre RCT provides supporting, though more nuanced, evidence. Across 244 adults at six hospitals in Southwest England, Oxford Hip Scores at 120 days were statistically similar between the SPAIRE and lateral arms (adjusted mean difference −1.23, 95% CI −3.96 to 1.49, p=0.37). Where the SPAIRE group did separate itself was in early postoperative pain: participant-reported pain at three days was lower in the SPAIRE arm. Length of stay, discharge destination, and 120-day survival were comparable between groups.

A 2024 case series by Kumar et al. (n=35, PMC11420420) recorded a mean time of 1.5 days to orthotic-assisted walking and a mean Harris Hip Score of 83.16 at two months following SPAIRE, with one dislocation — related to a fall at three months — and no infections or nerve injuries. A separate 2025 RCT (n=158) comparing SPAIRE and the direct anterior approach found equivalent periprosthetic bone mineral density changes at 12 months, suggesting SPAIRE's soft-tissue preservation carries no measurable bone-density penalty.

The lateral approach, for its part, carries decades of outcome data, a well-characterised dislocation profile, and established guidance in UK practice — strengths the shorter SPAIRE literature has not yet matched in volume or follow-up duration. Long-term comparative data beyond two years for elective total hip replacement remain limited. The NIHR-funded HIPSTER trial — a double-blinded, three-arm RCT testing tendon-sparing approaches against the standard posterior technique — is ongoing, and its results are awaited. Research, in short, is catching up with surgical practice rather than leading it.

Recovery in practice: precautions, pain, and getting mobile

For most patients, the choice of approach stops being abstract the moment they get home and face their own furniture.

After a lateral approach

Because the lateral approach partially detaches the gluteus medius and minimus, the repaired muscle needs protected time to heal. Most centres advise 4–6 weeks of abduction restrictions: patients are typically told not to cross their legs, to sit only on chairs high enough that the hip does not drop below knee level, and to sleep with a pillow between their legs for several weeks. For a patient living alone in a standard house — where kitchen chairs are low and sofas are deep — these restrictions require some practical preparation before the operation.

As the gluteus medius recovers, some patients notice a slight dip towards the operated side when walking (Trendelenburg gait, discussed in the previous section). In most cases this gradually resolves with physiotherapy, though the timeline varies between individuals.

After SPAIRE

Because the posterior restraint tendons remain in continuity throughout a SPAIRE procedure, many centres do not impose standard hip precautions afterwards. In practice, patients are often encouraged to sit at a normal chair height, cross their legs in a comfortable position, and move without the spatial rules that accompany other approaches. That said, what is permitted in the early weeks depends on each surgeon's own protocol and the individual patient's anatomy — it is not a blanket guarantee that applies to every SPAIRE case.

Rehabilitation for both

Muscle-sparing does not mean effort-free. Physiotherapy is important after both approaches: rebuilding confidence, gait pattern, and hip strength takes consistent work over weeks and months regardless of which surgical route was used. The difference lies mainly in what patients must avoid during that period, not whether recovery requires active engagement.

Which patients are suited to each approach

Neither approach suits every patient or every surgeon equally, and framing the choice as a personal preference misrepresents how the decision is actually made.

SPAIRE does not require the limb-positioning that the direct anterior approach demands, which supports its noted adaptability to patients with higher BMI or more complex hip anatomy. Where it becomes more technically demanding is in patients with small hip anatomy or significant external rotation deformity — scenarios in which the available working space narrows and technique-sensitive steps carry greater risk. Surgeon training and accumulated case volume matter considerably; SPAIRE is not a straightforward modification without a learning curve, and its outcomes reflect the experience of the surgeon performing it.

The lateral approach, by contrast, is reproducible across a wide anatomical range and does not depend on specialist posterior-corridor familiarity. It remains the NICE-recommended standard comparator for hip hemiarthroplasty in the UK and is the approach with which most hip surgeons carry the greatest cumulative experience. That familiarity has genuine clinical value and should not be dismissed.

One area where a posterior corridor may carry a practical advantage is revision surgery: re-entering the hip through a lateral window can be more technically demanding than approaching via a posterior route. For patients with a longer life expectancy or prior hardware, this is worth considering at the planning stage.

Ultimately, the appropriate recommendation depends on pre-operative imaging, individual anatomy, functional goals, and an honest appraisal of the surgeon's experience with each technique. A consultation with a surgeon who is conversant in multiple approaches — and who can explain the clinical reasoning behind a recommendation — gives patients the most reliable basis for that decision.

Questions to raise with your surgeon

Five questions are worth preparing before any hip replacement consultation, whichever approach is under discussion.

• Which approach do you routinely perform, and how many of these cases have you done? Volume and specific training are legitimate quality markers for both techniques.
• Will I need hip precautions after the operation — and if so, which ones, for how long, and what will physiotherapy involve? The answer should be precise, not vague reassurance.
• What is my personal dislocation risk, given my anatomy and activity goals? Previous hip surgery, hypermobility, or a very active lifestyle can all shift this calculation.
• Will robotic or image-guided assistance be used, and what does that mean for implant positioning in my case?
• If SPAIRE is being considered, have you completed specific training in the technique, and does my anatomy make me a suitable candidate?

A surgeon who can work through all five questions openly — explaining the clinical reasoning rather than offering blanket reassurance — gives patients the soundest basis for a decision they will live with for many years. Lincolnshire Hip is part of the MSK Doctors group and accepts patients without referral for hip assessment, with consultations available in Grantham and Sleaford.

1. [1] A Standard of Care in Hip Arthroplasty: Routine Use of the Tendon-Sparing SPAIRE Technique with MAKO Robotic Assistance. (2024). https://doi.org/10.1302/1358-992x.2024.16.030 https://doi.org/10.1302/1358-992x.2024.16.030
2. [2] SPAIRE approach shows equivalent changes in bone mineral density as a conventional approach in femoral neck fracture patients. (2025). https://doi.org/10.1302/2633-1462.64.BJO-2024-0171.R1 https://doi.org/10.1302/2633-1462.64.BJO-2024-0171.R1