Two tissue-sparing routes to the same operation

If you have come across both names and wondered whether you are being offered two different operations, the short answer is no. SPAIRE and SuperPATH are both total hip arthroplasty — the same prosthetic joint, placed the same way, with the same goal of relieving arthritis pain and restoring movement. What differs is the route the surgeon takes to reach the hip, and how the surrounding soft tissue is handled along the way.

Both techniques were developed as improvements on the traditional posterior approach, which has been the most widely used method for hip replacement in the UK for decades. That standard route requires the surgeon to cut through the posterior tendons — the short external rotator muscles at the back of the hip — to gain access to the joint. Recovery typically involves three to five days in hospital and a period of strict movement restrictions while those tendons heal.

SPAIRE and SuperPATH each take a different path to avoid that tendon damage. SPAIRE works through a posterior corridor but leaves key tendons completely intact. SuperPATH approaches the joint through a supracapsular channel above the hip capsule and never formally opens it. One technique spares the tendons; the other spares the capsule.

How each technique protects tissue around the hip joint

The hip joint is a ball-and-socket articulation — the rounded femoral head sitting within the cup-shaped acetabulum of the pelvis. At the back of the joint, a cluster of short muscles called the external rotators acts as the primary soft-tissue guard against the femoral head slipping backwards. Three of these muscles are central to any comparison of the two techniques: the piriformis, the obturator internus, and the obturator externus.

SPAIRE — which stands for Saves Piriformis And Internus with Repair of Externus — works through the posterior corridor but treats those tendons with precision rather than expediency. The piriformis and obturator internus are left entirely undisturbed throughout the procedure. The obturator externus is sectioned to allow adequate access, then carefully repaired before the wound is closed. The major stabilising tendons therefore remain structurally and functionally continuous — this is what makes SPAIRE a tendon-sparing technique.

SuperPATH takes a structurally different route. Working through a supracapsular corridor above the hip capsule, the surgeon prepares the femoral canal in situ using a separate percutaneous portal, without formally dislocating the femoral head. The capsule is never formally opened and remains wholly intact throughout — making SuperPATH a capsule-sparing technique.

Both approaches share the same underlying aim of reducing soft-tissue trauma compared with the traditional posterior route, but the structure each leaves untouched is not the same. That distinction shapes how stability is achieved after surgery, which suitability criteria apply, and what recovery may look like for different patients.

What keeps the hip stable after each approach

Dislocation risk is where the choice of approach has its sharpest clinical consequence — and where the tissue-preservation logic of both techniques becomes most tangible.

SPAIRE's primary defence against dislocation is what clinicians call the 'strap effect'. The intact obturator internus tendon wraps around the lesser sciatic notch and courses over the posterior femoral head close to the centre of rotation. Even at rest, this creates a continuous passive tether that aims to resist posteriorly directed forces on the femoral head; active muscle contraction increases that resistance further.

Alongside this mechanical tether, the preserved short external rotators carry undisturbed Golgi tendon organs and muscle spindles — the sensory receptors that report joint position and load to the nervous system. Because these mechanoreceptors remain intact after SPAIRE, the hip retains the proprioceptive feedback that allows it to reflexively self-protect against positions that might otherwise risk subluxation. Severing these structures, as conventional posterior surgery requires, leaves the joint neurologically less responsive until tissues heal.

SuperPATH achieves stability through a structurally different route. By working supracapsularly and never formally opening the capsule, the technique aims to remove the healing gap that drives the 90-day movement-restriction window — an intact capsular envelope provides a continuous structural boundary from the moment surgery is complete.

The downstream evidence underlines why both mechanisms matter. Published data indicate that 57% of patients who dislocate after hip replacement go on to dislocate more than once, and 45.6% require revision surgery within two years. Neither approach is designed to eliminate dislocation risk entirely, but both are built on the principle that tissue preserved during surgery continues working in the patient's favour afterwards.

Patient suitability: which approach fits which candidate

Choosing between these two approaches depends less on which technique sounds more appealing and more on whether a patient's anatomy and clinical picture make either one viable. Because no head-to-head randomised controlled trial comparing SPAIRE and SuperPATH has been published, that judgement rests on mechanistic reasoning, observational data, and individual surgical assessment rather than on controlled comparative evidence — a useful frame to carry through any comparison of the two.

SPAIRE is described as broadly applicable within the standard THA candidate population, with suitability confirmed case by case through imaging and clinical examination. Its posterior corridor gives the surgeon more anatomical working room than SuperPATH's supracapsular route. Where additional precision matters — for instance where anatomy makes visual access more limited — SPAIRE is compatible with Mako robotic-arm assistance, which provides sub-millimetre implant positioning and compensates for the more constrained exposure.

SuperPATH's access route carries stricter selection criteria. Working supracapsularly without formal dislocation of the femoral head requires clear, unobstructed anatomy: severe hip deformity, very high BMI, or complex structural variation typically exclude patients from this technique in most centres. The approach also demands specialised instrumentation and carries a steeper learning curve; outside high-volume specialist settings, the risk of stem malalignment is meaningfully elevated, making centre experience and surgeon caseload material factors in outcome.

Neither approach suits every THA candidate. A muscle-sparing posterior route — whether SPAIRE or another variant — may still be the wrong choice for a patient who would otherwise be a good replacement candidate, and individual anatomy sometimes steers the decision towards a different access corridor entirely. Suitability is always determined through assessment, imaging, and direct discussion between patient and surgeon.

Recovery, precautions, and what to expect after surgery

Movement restrictions are often patients' first practical concern once a tissue-sparing approach is mentioned — and both SPAIRE and SuperPATH are designed with exactly that in mind.

In traditional posterior hip replacement, the severed posterior tendons and capsule require time to heal before the joint can safely resist dislocation under everyday loading. That healing gap generates the formal precaution period — typically no hip flexion beyond 90°, no crossing the legs, no internal rotation — lasting up to 90 days, and it is associated with the longer inpatient stays that tissue-sparing techniques set out to reduce.

SPAIRE removes the structural basis for those restrictions in suitable patients. Because the piriformis and obturator internus are never severed, there is no equivalent healing gap: the mechanical tethers described earlier are functioning from the moment surgery is complete. Movement precautions may be relaxed or eliminated at the operating surgeon's discretion, depending on individual anatomy and intraoperative findings.

SuperPATH reaches the same goal by a different anatomical route. Keeping the capsule wholly intact means there is no capsular repair to protect — and, in principle, no capsular vulnerability window to manage. Early confident mobilisation is a core design aim, and the technique has been developed to support same-day discharge pathways where patient health and centre protocols allow.

Recovery still varies considerably between individuals. Age, fitness, body composition, baseline hip function, and implant fixation method all influence how quickly a patient mobilises and returns to daily activity. Faster recovery is the aim of both approaches, not a fixed outcome — and realistic discharge timing is something to discuss directly during a clinical assessment.

Getting the right approach assessed for your hip

Knowing the structural logic behind SPAIRE and SuperPATH matters — but the comparison only becomes clinically useful when applied to a specific patient's anatomy, imaging, and history. Neither technique is a universal default. Approach selection is a surgical decision, shaped by bone geometry, soft-tissue quality, BMI, deformity pattern, and the operating team's experience with each corridor. Patients who arrive at consultation already leaning towards one technique often find that the clinical picture steers the decision somewhere they hadn't anticipated.

For patients considering a tissue-sparing posterior approach, that assessment is available through Hip Replacement Lincolnshire, part of the MSK Doctors group. Prof Paul Lee, the consultant whose clinical approach informs this site's explanation of SPAIRE, sees patients at centres in Sleaford (NG34) and Grantham (NG31). The group accepts patients without referral, which removes the waiting-list delays typical of NHS pathways. Where relevant, pre-operative planning may draw on MAI Motion® gait and biomechanical assessment to support decision-making. Patients based in London can access the group's London arm, LCC, for equivalent consultant-led assessment.

To book an appointment, visit hipreplacementlincolnshire.co.uk.