What SPAIRE preserves — and why it changes your recovery

Recovery after SPAIRE hip replacement feels different from conventional posterior-approach surgery for one straightforward reason: the tendons that normally keep your hip joint stable have never been cut.

In a standard posterior hip replacement, the surgeon divides several of the short external rotator tendons — including the piriformis and obturator internus — to gain access to the joint. These are the hip's own posterior stabilising cuff, roughly analogous to the rotator cuff tendons of the shoulder. Dividing them creates a window of vulnerability after surgery, which is why conventional posterior-approach patients are given strict movement restrictions: no bending the hip beyond 90°, no crossing the legs, no twisting inward.

SPAIRE (Saving Piriformis And Internus, Repair Externus), first described by the Exeter Hip Unit in 2016, approaches the joint through the interval between the inferior gemellus and quadratus femoris. Only the obturator externus tendon is divided. The piriformis, superior gemellus, and obturator internus — the tendons that matter most for posterior stability — remain completely intact throughout the procedure. By 2024, the originating surgeon had used this approach in over 1,000 primary total hip replacements.

Because the stabilising soft-tissue envelope is never disrupted, the anatomical justification for conventional posterior dislocation precautions no longer applies. The joint is mechanically protected from day one — not by restrictions on your movement, but by tendons that were never cut in the first place.

A variant called Modified SPAIRE additionally divides the inferior gemellus for improved surgical exposure, then repairs it with strong trans-osseous sutures alongside the obturator externus and posterior capsule. It shares the same tendon-preserving philosophy and the same rationale for omitting standard posterior precautions.

Why posterior precautions do not apply after SPAIRE

The restrictions patients dread most — keeping the hip above 90°, never crossing the legs, avoiding any inward twist — exist for a specific mechanical reason in conventional posterior surgery: the stabilising tendons have been divided and reattached under tension. Until that repair heals, the joint is vulnerable, and movement restrictions substitute for the stability the tendons temporarily cannot provide.

After SPAIRE, that logic does not apply. The tendons were never divided, so there is nothing healing under tension, and no movement restriction compensates for a repair that was never made.

The wider evidence broadly supports this position. A 2024 systematic review and meta-analysis pooling three randomised controlled trials (n=1,215) found no statistically significant difference in dislocation rates when posterior-approach total hip replacement was performed with or without formal hip precautions. The patients managed without precautions also showed better HOOS JR patient-reported outcomes and achieved walking-aid independence faster — findings that led the authors to conclude, explicitly, that posterior-approach THA does not require hip precautions.

Those trials used conventional posterior approaches in which tendons were divided. SPAIRE's intact soft-tissue envelope provides an even stronger mechanistic case for omitting restrictions, though SPAIRE-specific dislocation data are still being collected prospectively and are discussed in the final section.

One qualification is worth stating clearly: this is approach-specific guidance, not a general relaxation of post-operative hip safety. The basis for unrestricted movement after SPAIRE is the anatomy of this particular technique — piriformis and obturator internus intact, posterior stability preserved from the moment the patient wakes from surgery.

Early mobilisation: criteria for leaving hospital

Getting up after SPAIRE hip replacement is guided by what your body can do, not by how many hours have elapsed since surgery.

A 2025 prospective study of 237 THA patients found no meaningful difference in Timed Up and Go performance, pain scores, walking independence, or time to meeting ambulatory discharge criteria between patients mobilised within 8 hours of surgery and those mobilised at 12–24 hours. The practical implication is that the clinical team will assess readiness against specific physical markers — not a minimum time threshold.

One common early barrier is orthostatic intolerance: the dizziness or light-headedness that affects around 30% of THA patients when they first sit or stand, typically in the first four to six hours post-operatively. This is a normal post-anaesthetic phenomenon, not a warning sign. A 2025 feasibility study found that repeated, supervised mobilisation attempts resolved orthostatic intolerance in 76% of affected patients by five hours, and in the remainder by six hours.

The discharge milestone cluster is practical and consistent: independent walking with a walking aid, the ability to negotiate stairs, adequate pain control on oral medication, and a wound that is clean and dry.

Because posterior precautions are absent after SPAIRE, there are no arbitrary restrictions on sitting height, chair choice, or foot-care tasks during this phase. Patients can sit in a normal chair and attend to dressing or footwear without the awkward adaptations that conventional posterior-approach recovery demands — a small but meaningful gain in early independence.

Progressive milestones from discharge to return to activity

Recovery from discharge onwards moves in clusters of functional achievement rather than along a fixed weekly schedule.

Walking aid weaning

The shift from two crutches to one, and ultimately to none, follows gait symmetry and single-leg stability. After SPAIRE, no concurrent soft-tissue repair penalises early loading, so progression can happen as soon as stride symmetry is present and the patient can briefly stand on the operated leg without Trendelenburg drop.

Mid-phase markers

Stair confidence — negotiating a full flight without side-stepping or rail dependency — reflects quadriceps strength and hip control. Trendelenburg control during single-leg stance on the operated side is the key abductor marker; pain-free weight-bearing through a full gait cycle without antalgic limp signals readiness for longer walks and more varied terrain.

Driving

Returning to driving is criteria-based. If the operated leg is the braking foot, clinicians require demonstrated pain-free seated hip flexion, quick dorsiflexion, and the ability to perform an emergency stop safely — not a fixed number of weeks. This is typically assessed at the six-week follow-up appointment.

Return to leisure

Hip ROM, abductor strength, and patient confidence together determine when leisure activities resume. Stationary cycling, swimming, and longer walks are practical early targets once the wound has healed; more demanding activities such as golf or hiking follow when hip control is consistent.

Variability

Pre-operative fitness is the factor that most reliably predicts how quickly these milestones arrive. Patients who enter surgery with stronger abductors, better cardiovascular fitness, and a healthy body weight tend to progress faster — SPAIRE removes the artificial constraint of precautions, but muscle reactivation, bone remodelling around the implant, and recovery from anaesthesia each follow their own biological pace. Age and adherence to rehabilitation exercise contribute meaningfully too; patients should expect genuine variation rather than a fixed schedule.

How implant positioning supports safe unrestricted movement

Safe unrestricted movement after SPAIRE depends not only on what the surgeon preserves, but on how accurately the new implant replicates the hip's natural mechanics.

Femoral offset — the horizontal distance between the centre of the femoral head and the femur's long axis — determines the lever arm through which the abductor muscles work. When offset is restored correctly, the abductors generate normal force and the hip is mechanically stable from the first step. When offset falls short, the lever arm shortens, muscle force drops, and dislocation risk rises regardless of precaution status. Accurate cup orientation (anteversion) matters equally: together, a correctly positioned socket and correctly offset stem recreate the mechanical environment the patient's body was built around.

This is where intraoperative precision contributes. MAKO robotic assistance allows detailed biomechanical planning before surgery and real-time verification of implant position during it — particularly useful in anatomically challenging cases, such as patients with small anatomy, reduced native offset, or an external rotation deformity, where manual estimation carries greater uncertainty.

In the Lincolnshire context specifically, Prof Paul Y. F. Lee uses MAKO alongside the SPAIRE technique as standard practice. That combination means the mechanical foundation — stable implant, restored offset, correct cup orientation — is already verified before the patient leaves theatre. Criteria-based, precaution-free rehabilitation then follows as a biomechanical consequence, not simply a policy decision.

What the ongoing NIHR trials will add to SPAIRE rehab guidance

Two NIHR-funded trials are now directly addressing the one gap this article has flagged throughout: the absence of formally validated, SPAIRE-specific milestone data.

The HIPSTER trial (HIP Surgical Techniques to Enhance Rehabilitation) is a three-arm, double-blinded RCT comparing piriformis-sparing, SPAIRE, and standard posterior approaches in primary total hip replacement, with speed of post-operative mobilisation and return to unrestricted function as primary endpoints. It is the first study designed from the outset to quantify what SPAIRE-specific rehab progression looks like in controlled conditions. The companion HemiSPAIRE RCT — recruiting between November 2019 and April 2022 — extends this question to SPAIRE in hip hemiarthroplasty for displaced intracapsular fractures.

Until both trials report, the criteria-based framework described in this article rests on two substantial pillars: the broader no-precautions THA literature, which found identical dislocation rates and superior patient-reported outcomes without restrictions, and the anatomical logic of sparing the posterior rotator cuff entirely. These are not provisional placeholders — they are the most directly applicable evidence currently available.

When HIPSTER reports, it is expected to formalise milestone criteria specific to SPAIRE's soft-tissue profile, giving clinicians and patients validated targets where currently they work from principle and adjacent data. Formalised SPAIRE-specific timelines remain pending; what already exists is a coherent, evidence-grounded case that the biology of this approach supports unrestricted recovery from the outset.

1. [1] Feasibility of Repeated Early Mobilization in Orthostatic Intolerance After Total Hip Arthroplasty. (2025). https://doi.org/10.1016/j.ijotn.2025.101187 https://doi.org/10.1016/j.ijotn.2025.101187
2. [2] Effects of Very Early versus Early Mobilization and Walking on Functional and Psychosocial Outcomes After Total Hip Arthroplasty. (2025). https://doi.org/10.1016/j.artd.2025.101933 https://doi.org/10.1016/j.artd.2025.101933
3. [3] 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
4. [4] No Need for Hip Precautions After Total Hip Arthroplasty with Posterior Approach: A Systematic Review and Meta-Analysis. (2024). https://doi.org/10.1097/MD.0000000000040348 https://doi.org/10.1097/MD.0000000000040348
5. [5] The SPAIRE Technique Allows Hip Arthroplasty with Division of Only the Obturator Externus Tendon. (2018).
6. [6] The SPAIRE Technique (Spare Piriformis and Internus, Repair Externus) for Hip Arthroplasty is Safe and Effective. (2018).