Two treatments, one disease — at different stages

Most patients arrive at this question framing it as a contest — repair versus replacement, as if one must be superior to the other. In practice, the two procedures treat the same hip joint disease at different points in its progression. Choosing between them is not a matter of preference; it is a matter of timing.

Three variables interlock to determine which pathway is appropriate at any given moment: the stage of osteoarthritis, the size and depth of the cartilage defect, and the patient's age. When all three are assessed together, they point toward one of four escalating steps — protecting and managing the joint, fixing structural problems such as impingement or labral tears, rebuilding damaged cartilage with biological techniques or scaffolds, and, when those options are no longer viable, replacing the joint. Hip replacement sits at the end of that sequence, not in competition with what precedes it.

The clinical question, then, is never simply 'which is better?' It is: which is right for this hip, at this stage of this disease? The sections below work through that question systematically.

OA stage: the primary gate

The first — and most consequential — question is where cartilage damage falls on the disease spectrum.

When the hip joint contains a focal lesion — a defined, bounded area of cartilage loss against an otherwise intact joint surface — the structure is still worth preserving. These focal defects are the target for cartilage repair and preservation surgery. The ICRS (International Cartilage Repair Society) grading system describes lesion depth in four steps: Grade 1 indicates surface softening only; Grade 2 lesions extend less than half the cartilage thickness; Grade 3 lesions exceed 50% depth; and Grade 4 lesions penetrate through the subchondral bone entirely. Grades 3 and 4 indicate structural failure requiring more advanced reconstruction — straightforward marrow stimulation is insufficient at this depth — but repair remains viable provided the damage is focal rather than diffuse.

When the whole hip joint surface has worn through in a bone-on-bone pattern, the picture is fundamentally different. Diffuse, end-stage osteoarthritis affecting the full hip articulation is not suitable for cartilage repair; hip replacement becomes the correct and definitive next step.

Femoroacetabular impingement (FAI) — a common cause of focal cartilage damage in younger adults — is relevant here as one of the precursors that can establish the focal defect pattern; its role in the preservation pathway is discussed in greater detail later.

OA stage, in short, is the gate through which every other decision must pass. The size of the defect and the patient's age — addressed in the following sections — only become meaningful questions once damage is confirmed as still focal enough for repair to be viable.

Defect size and which repair technique fits the hip

Surface area is the next variable once OA stage confirms that a focal defect is present and worth repairing.

For smaller lesions — roughly under 2 cm² — osteochondral autograft transfer (OATS or mosaicplasty) is one established single-stage option, transplanting a cylinder of healthy cartilage and bone from a low-load area of the hip to fill the defect. AMIC (autologous matrix-induced chondrogenesis) occupies similar territory: it combines marrow stimulation with a protective collagen matrix, bridging the gap between simple marrow stimulation and the more resource-intensive cell-based techniques.

For suitable focal hip cartilage defects that do not require theatre-based surgery, ChondroFiller injection — an acellular injectable collagen scaffold delivered as an ultrasound-guided outpatient treatment — works by a different mechanism. The scaffold self-gels within the defect and recruits the patient's own progenitor cells through matrix-induced chondrogenesis. It is not suitable once advanced arthritis is present.

For larger defects in the 2–10 cm² range, MACI (matrix-induced autologous chondrocyte implantation) carries solid mid-term evidence: the SUMMIT trial showed superior pain and function scores over microfracture at five years for defects of ≥3 cm². MACI is two-stage — biopsy first, then cell culture and re-implantation on a collagen membrane. Where even MACI is insufficient, such as in large posttraumatic lesions, fresh osteochondral allograft (OCA) transfers both cartilage and bone from a donor graft.

Microfracture no longer fits as a first-line modern choice. It produces fibrocartilage rather than true hyaline cartilage, outcomes in published series typically begin to decline after two to three years, and the technique damages the subchondral bone plate — narrowing the options for any repair procedure attempted afterwards.

It is worth noting that hip-specific randomised trial data remains more limited than the equivalent knee evidence; many defect-size thresholds are adapted from knee studies. Even so, the technique ladder is well enough defined that selecting the right tool for the lesion — by area, depth, and subchondral status — is the clearest way to give a hip cartilage repair its best chance of lasting.

Why age changes the calculation

Implant longevity sits at the heart of why age matters in this decision. Approximately 58% of total hip replacements are estimated to last 25 years — a figure that carries very different weight depending on when the operation takes place. A patient who has a hip replacement at 45 will, in most scenarios, outlive their implant; the revision that follows tends to be technically more demanding and carries a lower prospect of success than the original procedure. That long-term arithmetic is the main clinical argument for exhausting all reasonable hip preservation options in younger, more active patients before committing to replacement.

For older patients — where the remaining biological demand on the joint is lower and advanced OA has already made repair impractical — the calculation reverses. Hip replacement is then not only appropriate but generally the most effective pathway to restoring function and relieving pain.

Between the two sits hip resurfacing: a bone-preserving option that places a metal cap over the femoral head rather than removing it entirely, leaving more native bone stock intact than a standard total hip replacement. Published evidence supports meaningful improvement in health-related quality of life after resurfacing in suitable patients, and it is particularly studied in younger, more active men, though it is not appropriate for all hip anatomies or OA patterns.

Age is not, however, a hard threshold. It compounds with OA stage and defect size rather than acting alone. A 45-year-old whose hip has reached diffuse, bone-on-bone osteoarthritis may be a more appropriate replacement candidate than a 60-year-old presenting with a clearly bounded focal defect well within the range of cartilage repair. The decision is individually assessed — shaped by the full picture, not age in isolation.

Before surgery: injections, FAI treatment, and slowing progression

The sections above map the surgical decision — which repair technique, and when replacement becomes appropriate. For many patients with early hip pain or a recently identified cartilage problem, the more immediate question is what comes before that decision becomes necessary. This upstream layer is where injections sit, and where treating the underlying mechanical causes of cartilage wear — including FAI — can make the most difference.

Intra-articular injections are the most commonly used tools at this stage. Both corticosteroid and hyaluronic acid (viscosupplementation) injections have randomised trial support for symptomatic hip osteoarthritis: they reduce pain, help maintain mobility, and repeated courses of viscosupplementation show sustained effectiveness in early-to-moderate disease. What injections do not do is repair a structural defect. If a focal cartilage lesion is already present, an injection manages the joint environment around it — not the lesion itself. That distinction matters when deciding whether injection therapy is a bridge toward a repair procedure, or a longer-term conservative strategy while the joint remains stable.

As discussed earlier, FAI — caused by bone shape abnormalities generating abnormal hip contact — is a common and treatable precursor to focal cartilage damage. Addressing impingement before significant cartilage loss has occurred can interrupt the progression that eventually tips the balance toward repair or, further along, replacement.

Biologic injections such as PRP or BMAC may feature as adjuncts within a broader preservation plan, supporting the joint environment alongside other treatments rather than serving as a standalone repair strategy.

The hip pathway at Lincolnshire Hip

Pulling the key variables together — OA stage, defect size, and individual age and activity level — is what an initial hip assessment is designed to do. Imaging, clinical history, lesion staging, and a clear account of activity goals all feed into the recommendation. For a patient with a focal defect at an early OA stage, the staged preservation pathway offers a realistic route to extending joint life before replacement becomes necessary; for someone presenting with diffuse, end-stage osteoarthritis, replacement is the most reliable means of restoring function and relieving pain. The same variables can point in different directions depending on how they sit together for any one person — which is why a consultant-led assessment is the necessary starting point rather than a self-directed decision.

For patients whose assessment confirms that replacement is the right next step, Professor Paul Y. F. Lee's experience is directly relevant. He has published on hip pain management and peri-operative hip replacement care, and his use of the SPAIRE technique — which preserves the muscles that stabilise the hip joint after surgery — aims to reduce post-operative discomfort and lower the risk of dislocation during recovery.

Lincolnshire Hip is part of the MSK Doctors group and accepts patients without referral for hip assessment at Sleaford and Grantham — a practical first step for anyone across the non-London catchment to establish where they sit on the pathway and what their realistic options are.

1. [1] Hip replacement. https://en.wikipedia.org/?curid=1125423 https://en.wikipedia.org/?curid=1125423
2. [2] Osteoarthritis. https://en.wikipedia.org/?curid=504841 https://en.wikipedia.org/?curid=504841
3. [3] Hip resurfacing. https://en.wikipedia.org/?curid=11133475 https://en.wikipedia.org/?curid=11133475