How disease stage drives the decision

The single most useful question a clinician can answer early in a hip consultation is not "how much does it hurt?" but "where is this joint on the scale of damage?" Pain intensity and structural change are often poorly correlated, and it is the structural picture — not the pain score alone — that shapes what remains possible.

Orthopaedic surgeons use the Kellgren-Lawrence (KL) grading system to standardise that assessment. Grades 0 and 1 describe a normal or near-normal hip joint; Grade 2 marks the threshold at which true osteoarthritis is considered present, with definite osteophytes and possible joint space narrowing. Grades 3 and 4 bring multiple osteophytes, clear joint space loss, subchondral sclerosis, and — at Grade 4 — major bone deformity. As a working rule, the preservation window sits at KL 0 to 2; Grades 3 and 4 shift the conversation towards replacement.

A second gate sits alongside OA grade: whether the cartilage damage is focal or diffuse. A single, contained defect in an otherwise intact joint responds very differently from widespread surface loss across the whole joint. This distinction — not age alone — determines whether restoration techniques are realistic.

For patients with femoroacetabular impingement, Tonnis grading adds a further layer. UK Non-Arthroplasty Hip Registry data show that two-thirds of FAI arthroscopy patients achieve a clinically meaningful improvement by six to twelve months — but that figure falls sharply at Tonnis grade 2 or higher, where conversion to total hip replacement is substantially more likely.

The preservation window — who is a repair candidate

Plenty of patients in their 40s and 50s arrive at a consultation wondering whether they have left it too late for anything other than replacement. The honest answer is: it depends on what the imaging shows — and age alone is not the deciding factor.

The key question is defect character. A focal, contained area of cartilage loss — typically under 4 cm², roughly the surface area of a fingernail — in a hip joint that is otherwise intact puts preservation firmly on the table, even in mid-life. What removes it is diffuse cartilage loss, established moderate-to-severe OA, or bone-on-bone contact: damage that has spread beyond a repairable patch and changed the architecture of the joint as a whole. Treatment selection is also shaped by the patient's activity level and the size of the affected area, both of which influence what a repair can realistically achieve.

For patients dealing with femoroacetabular impingement and labral damage alongside focal cartilage changes, the picture becomes more nuanced with age. In patients over 40, labral reconstruction produces a meaningfully lower revision rate than labral repair — 7.4% versus 20.7% in published data — making technique selection a live clinical question rather than a formality.

Three clear disqualifiers close the preservation window: Tonnis grade 2 or higher OA confirmed on pre-operative imaging, bone-on-bone contact, and a history of failed prior cartilage repair procedures. Once any of these applies, further preservation attempts are unlikely to succeed and may delay access to a replacement the joint genuinely needs.

With the eligible patient profile established, the following section sets out which repair options are currently available and what each one involves.

Cartilage repair routes available in the UK

Several routes exist for patients who fall within the preservation window described above, ranging from an outpatient injection to a day-case surgical procedure.

ChondroFiller injection

For many patients, the most accessible starting point is the ChondroFiller injection — an acellular injectable collagen scaffold delivered as an ultrasound-guided outpatient procedure. Rather than introducing foreign cells, the scaffold works by recruiting the patient's own progenitor cells into the defect site, a process called matrix-induced chondrogenesis. The device is CE-marked as a Class III medical product and, in published hip outcomes data, has been associated with an improvement in the modified Harris Hip Score of approximately 30 points. It is available through Lincolnshire Hip as part of the non-surgical pathway.

AMIC

Autologous Matrix-Induced Chondrogenesis (AMIC) occupies the middle ground between marrow stimulation and full cell-based repair: it combines the bone-drilling step of microfracture with a bio-absorbable membrane to guide tissue formation. It is a single-stage, NICE-approved procedure with results broadly comparable to the two-stage Autologous Chondrocyte Implantation (ACI) approach, though it is not yet widely available specifically for hip joints.

Microfracture

Microfracture was historically the first-line technique for small focal defects. Current evidence, however, consistently shows that the fibrocartilage it produces begins to break down at around two to three years, and the procedure can damage the subchondral bone plate in ways that compromise future repair options. It is now considered a declining approach rather than a current first choice.

ACI and MACI

ACI and its matrix variant MACI are NICE-approved for the knee, but the deep ball-and-socket geometry of the hip joint makes cell implantation extremely technically difficult; neither is standard practice for hip cartilage repair in the UK.

Arthrosamid and PRP

Arthrosamid — a non-degradable polyacrylamide hydrogel — and platelet-rich plasma (PRP) are also available at Lincolnshire Hip, but they serve different roles: Arthrosamid provides volume support within the joint rather than regenerating tissue, while PRP acts as a biologic adjunct to reduce inflammation and support healing. Neither is a cartilage scaffold.

When hip replacement is the right call

Reaching the threshold for hip replacement is not a clinical failure — it is a recognition that the joint has changed beyond what repair can address, and that the most effective intervention is now a different one.

NHS guidance sets out four criteria that, taken together, indicate replacement is appropriate: persistent hip pain that disrupts daily life, meaningful functional loss (difficulty walking, dressing, or sleeping), failure of conservative treatment including physiotherapy and analgesia, and radiological confirmation of moderate-to-severe osteoarthritis — Kellgren-Lawrence grades 3 to 4. Patients who assume they are ineligible because of weight or other health factors may be surprised to learn that many NHS Integrated Care Boards will waive strict BMI or scoring thresholds when imaging confirms severe bone-on-bone destruction, because delaying surgery at that stage makes any future intervention substantially harder.

On outcomes, the National Joint Registry's 22nd Annual Report (2025) records nearly 1.7 million primary hip replacements entered into the registry up to December 2024. Revision rates at every measured interval — 3, 5, 7, 10, and 13 years — have improved year-on-year since approximately 2008. The NJR also cautions explicitly that a one-size-fits-all approach to implant selection is unlikely to produce uniformly good results; fixation method, bearing surface, and materials should be matched to the individual patient.

At Lincolnshire Hip, where clinically appropriate, Professor Paul Lee uses the SPAIRE technique — a posterior approach that preserves the short external rotators and posterior capsule. In plain terms, the muscles that normally stabilise the hip after a standard posterior replacement are left intact, with the aim of reducing post-operative pain, supporting joint stability, and enabling earlier mobilisation.

How much these considerations shift in younger or more active patients is addressed in the following section.

Age, activity, and what each path asks of you

Treatment choice is not only a question of what the hip joint looks like today — it is a question of what the patient wants their life to look like in ten or twenty years' time.

Consider two patients. The first is in their late 40s, still running regularly, and has a focal cartilage defect with no meaningful joint space loss. For this person, a hip replacement would require permanently avoiding high-impact loading — running, contact sport, heavy impact activity — to protect the implant from premature wear. That is a significant trade-off for someone whose activity is central to their wellbeing. A well-matched cartilage repair or scaffold injection that maintains near-normal function for a decade or more may represent a considerably better outcome for that individual, even if it does not rule out replacement later.

The second patient is in their early 60s with Kellgren-Lawrence grade 4 osteoarthritis, bone-on-bone contact confirmed on imaging, and persistent pain that has not responded to physiotherapy, analgesia, or injection-based support. Further preservation attempts are unlikely to improve on that picture; hip replacement is the evidence-supported next step, and the activity restrictions that concern a younger patient are far less relevant to someone whose primary goal is pain relief and regaining independence in daily tasks.

The underlying question is how many procedures a patient is prepared to undergo across a lifetime, and what level of activity they are trying to protect. Those answers vary enormously from person to person. Shared decision-making with a consultant who manages the full spectrum — from injection-based preservation through to replacement — is the most reliable way to avoid either premature surgery or unnecessary delay.

The Lincolnshire Hip full-pathway service

For patients in Lincolnshire and the surrounding area, the practical challenge is often access: finding a hip-only specialist who can assess, treat, and follow up without requiring repeated trips to London.

Lincolnshire Hip is led by Professor Paul Lee (GMC: 6115197), whose clinical remit covers the complete hip treatment pathway — from injection-based preservation through to surgical hip replacement. Assessment consultations, open MRI, ChondroFiller injection, Arthrosamid, PRP, and post-operative physiotherapy all take place locally at clinics in Grantham and Sleaford. Where surgery is indicated, Professor Lee operates at Weymouth Street Hospital in London, with a door-to-door private car service included in the package — so travel is managed rather than left to the patient to arrange.

Having a single specialist across the full spectrum matters when the clinical decision is genuinely in the balance. There is no handover between a preservation clinic and a replacement surgeon; the same clinician who considers a ChondroFiller injection in year one is the one who would perform a SPAIRE hip replacement if that becomes the right next step.

Lincolnshire Hip is part of the MSK Doctors group and accepts patients without referral for hip assessment.