What these two techniques have in common

Despite their different names and distinct surgical steps, SPAIRE and SuperPATH are not two separate categories of operation — they are two refinements of the same underlying route to total hip arthroplasty. Both are posterior-approach procedures, meaning the surgeon reaches the hip from behind the patient rather than from the front or side. And in both cases, the end result for the patient is a full hip replacement: the worn acetabulum (hip socket) and femoral head (ball) are removed and replaced with prosthetic components. Roughly 58% of total hip replacements are estimated to last 25 years, and patients receiving either technique are part of that same evidence base.

To understand what unites them, it helps to know what the standard posterior approach involves. Conventionally, reaching the hip joint from behind requires dividing several small tendons at the back of the hip — chiefly the piriformis and obturator internus — to create the surgical window. Those tendons normally help stabilise the hip mechanically and carry nerve endings that tell the joint where it is in space. Dividing them has historically meant a three-to-five-day hospital stay and, once patients go home, six weeks of strict movement restrictions: no bending past 90°, no crossing the legs, no turning the toes inward.

Both SPAIRE and SuperPATH were designed specifically to avoid that tendon sacrifice. Because the posterior short rotators remain intact in both approaches, neither technique requires those six-week precautions. That shared goal — preserving the tendons the standard posterior approach severs — is the clearest common ground between them. Where the two techniques diverge most sharply is at the moment of surgical exposure itself: how each surgeon gains access to the joint once those tendons are out of harm's way.

The sharpest anatomical difference between them

The sharpest distinguishing question between these two techniques is a straightforward one: does the femoral head — the ball — leave the socket at any point during surgery?

In SPAIRE (Saving Piriformis And Internus, Repair Externus), the answer is yes — briefly. The piriformis and obturator internus tendons are left completely untouched throughout. Access is gained by dividing only the obturator externus tendon, which allows the surgeon to open the joint capsule, temporarily dislocate the femoral head to place the prosthetic components, and then repair both the obturator externus and the capsule meticulously before closing. First described in 2016 at the Exeter Hip Unit, the technique as practised in specialist settings — including by Prof Paul Lee — involves this carefully controlled, temporary dislocation as the means of creating the working space needed to position implants accurately, while keeping the two most important stabilising tendons entirely intact throughout.

In SuperPATH, the answer is no. The entire procedure is conducted through a supracapsular corridor — a narrow channel that runs above the joint capsule without opening it. Because the surgeon works above rather than through the capsule, the femoral head never leaves the acetabulum at any point during the operation. Components are inserted through this small percutaneous window without the joint being dislocated at all.

This is not a minor technical footnote. Whether the hip is dislocated intraoperatively affects the degree of soft-tissue disruption during surgery, the mechanism the hip depends on for post-operative stability, and how quickly patients can bear full weight afterwards. Both approaches stand apart from standard posterior total hip arthroplasty, which requires dividing multiple posterior tendons to gain access — a step neither SPAIRE nor SuperPATH needs.

How each technique achieves hip stability

Stability in hip replacement depends on more than how securely the implant sits in the socket — the surrounding soft tissues play an active role, and these two techniques enlist them in fundamentally different ways.

SPAIRE's stability rests on two reinforcing mechanisms working in parallel. The first is mechanical: keeping the piriformis and obturator internus tendons entirely intact creates a natural restraint at the back of the hip — a 'strap effect' that physically checks the joint against the extreme positions most associated with post-operative dislocation. The second mechanism is neurological. Those same tendons contain Golgi tendon organs and muscle spindles — specialised receptors that continuously relay the hip's position to the central nervous system. In plain terms, they act as the joint's positional awareness system, telling the brain in real time where the hip is and triggering protective reflexes before a dislocation can occur. Standard posterior total hip arthroplasty severs these receptors, leaving the joint neurologically unaware during the weeks of biological healing. SPAIRE avoids that gap entirely by leaving the tendons — and their nerve endings — undisturbed from the first incision to closure.

SuperPATH's stability argument starts from a different premise altogether. Because the surgeon never opens the capsule or moves the femoral head during the operation, there is no soft-tissue disruption from intraoperative dislocation to recover from. The hip emerges from surgery in a mechanically undisturbed state, which supports very early weight-bearing without depending on tendon continuity for post-operative protection.

Two techniques, two distinct logic chains, the same destination: a durable, stable hip replacement with no post-operative movement restrictions required. Whether one produces fewer dislocations than the other in clinical practice is covered in the evidence section below.

What the current evidence shows

SuperPATH's evidence base against conventional total hip arthroplasty is now substantive. A 2025 systematic review and meta-analysis pooled nine randomised controlled trials — 299 SuperPATH patients against 379 receiving traditional hip replacement — and found SuperPATH consistently associated with shorter incision length, shorter hospitalisation, lower post-operative pain scores, and better early hip function. These are RCT-level findings, not observational observations, and they position SuperPATH firmly ahead of standard posterior THA on early recovery metrics.

SPAIRE's evidence profile is different in character. A published case series spanning from February 2016 onwards documents more than 1,026 routine primary total hip replacements performed with the technique — a meaningful volume for a surgical series, particularly from a single practice. What the field still lacks is a large, controlled trial with blinded outcome measurement. That gap is actively being addressed. The HIPSTER trial (HIP Surgical Techniques to Enhance Rehabilitation), funded by the NIHR, is a single-centre, double-blinded, three-arm RCT comparing robotic-assisted SPAIRE directly against piriformis-sparing and standard posterior total hip arthroplasty on speed of mobilisation and return to unrestricted function. Its results are awaited.

The critical evidence gap is direct comparison between SPAIRE and SuperPATH. No published RCT has placed both techniques in the same trial against each other. The comparative picture that currently exists rests on technical descriptions, mechanistic arguments, and indirect inference — not head-to-head data. The 2025 SuperPATH meta-analysis findings apply specifically to SuperPATH versus conventional THA; they cannot be read as a comparison with SPAIRE.

The evidence landscape is also still broadening at its edges: a 2026 retrospective cohort study comparing SuperPATH against the Hardinge (lateral) approach adds to the picture but does not resolve the SPAIRE-versus-SuperPATH question.

What this means practically is that both techniques are well-described and mechanistically coherent, but a clinician choosing between them is currently working from technique rationale and early-recovery logic rather than from a direct comparative trial. That direct comparison remains the outstanding research question.

Which patients tend to suit each approach

Anatomy, body type, and surgical complexity all influence which technique is likely to be offered — and whether a given surgeon is best placed to perform it.

SPAIRE uses standard posterior-approach instrumentation, which means the operating corridor is familiar to any surgeon trained in posterior total hip arthroplasty. The incision can be extended without complication if intraoperative exposure proves inadequate — a practical safety net that makes the technique adaptable across a wide range of body types, including patients with higher BMI or more complex bone anatomy. Because the piriformis and obturator internus are left entirely intact, only the obturator externus requires reattachment at closure; the repair burden is lower than in standard posterior total hip arthroplasty, which may matter for patients where soft-tissue healing capacity is a concern.

SuperPATH places different demands on both patient and surgeon. The technique requires specialised, highly targeted instrumentation and carries a recognised steep learning curve. It is generally considered most suited to patients with lower BMI and straightforward hip geometry; significant bone deformity or extreme body habitus may make the approach technically difficult or unsuitable in some cases.

Neither technique is universally available. Both depend on surgeon-specific training, centre equipment, and caseload volume. Surgeons such as Prof Paul Lee — who has used the SPAIRE technique in more than 1,000 routine primary hip replacements since February 2016 — typically assess each patient's anatomy, bone geometry, BMI, and activity goals individually before advising on approach. The relevant question is not which technique sounds preferable in principle, but whether the operating surgeon has the case experience and instrumentation to perform it safely for that individual.

Shared decision-making between patient and specialist is the appropriate model. A full clinical review of hip anatomy, bone quality, BMI, and activity goals remains the necessary first step before any technique is proposed.

Getting a specialist assessment for muscle-sparing hip replacement

Comparing these two techniques is useful context for any patient preparing for a surgical conversation — but technique preference alone is not a sufficient basis for operative planning. The anatomy of an individual hip, the patient's BMI and bone geometry, the surgical team's specific training, and the available instrumentation are the factors that ultimately determine which approach is appropriate. Both SPAIRE and SuperPATH are sound where they are well-matched to patient and surgeon; neither suits every case.

For patients considering a specialist assessment, Hip Replacement Lincolnshire — part of the MSK Doctors group — offers consultant-led appointments at Sleaford (NG34) and Grantham (NG31), without GP referral and without NHS-style waiting times. Prof Paul Lee, whose clinical approach informs the SPAIRE content on this site, sees patients considering muscle-sparing posterior arthroplasty and discusses technique suitability in the context of individual anatomy and goals. Where relevant, objective gait and biomechanical evaluation using MAI Motion® can provide a quantified functional baseline before surgery and a point of comparison during recovery. Further information and appointments are available at hipreplacementlincolnshire.co.uk.

The distinction between these two techniques — one that preserves tendons while briefly dislocating the joint, the other that never opens the capsule at all — is clinically meaningful enough to inform a genuine surgical conversation. Understanding the mechanism behind each approach, and where the current evidence sits, puts patients in a better position to weigh options with their operating surgeon.

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] The SPAIRE technique allows sparing of the piriformis and internus in hip arthroplasty. (2017). https://pubmed.ncbi.nlm.nih.gov/28218374/ https://pubmed.ncbi.nlm.nih.gov/28218374/
3. [3] SuperPATH versus traditional hip replacement in efficacy and safety: an updated systematic review and meta-analysis. (2025). https://doi.org/10.1186/s12891-025-08471-9 https://doi.org/10.1186/s12891-025-08471-9