Osteoartritis de rodilla: infiltraciones y evidencia clínica

La osteoartritis de rodilla es una enfermedad crónica caracterizada por dolor, rigidez y limitación funcional. Su diagnóstico es principalmente clínico: no se requiere radiografía en un cuadro típico, y la imagen solo se solicita ante presentaciones atípicas, traumatismo o duda diagnóstica. El objetivo terapéutico no es regenerar el cartílago, sino reducir síntomas, conservar movilidad y mantener la participación social de la persona.

Las infiltraciones intraarticulares de ácido hialurónico y plasma rico en plaquetas se han popularizado para el dolor persistente. Ninguna ha demostrado de forma consistente un efecto modificador de la enfermedad. Sus resultados dependen del producto, la preparación, la dosis, el comparador y la medida de resultado. Esta revisión analiza las recomendaciones de guías relevantes mediante el marco GRADE, con atención al tamaño absoluto del beneficio y su relevancia clínica.

En la consulta, ambas técnicas ocupan una posición secundaria tras educación, ejercicio, manejo del peso cuando procede y tratamiento farmacológico según el riesgo. La indicación debe derivarse de una decisión compartida, con objetivos realistas y preference for conservative care. Understanding the differences between these options is essential for appropriate patient selection.

El tratamiento que debe precede a las infiltraciones

El eje del manejo es el tratamiento conservador. La educación sobre la enfermedad, el ejercicio TERRE?<condition> must be tailored to the person’s functional limitations, and individual and group sessions may be offered. When appropriate, weight loss can reduce knee loading and improve symptoms, although it should be framed as a health intervention rather than a moral obligation. Activity modification should preserve movement while avoiding prolonged unloading or complete inactivity.

The pharmacological ladder is adapted to comorbidities and gastrointestinal, renal, and cardiovascular risk. Topical NSAIDs are often a reasonable first option for knee osteoarthritis because they provide local exposure with less systemic exposure than oral drugs. Oral NSAIDs may be considered if topical treatment is insufficient, provided there are no contraindications. Paracetamol has a smaller effect on pain, while weak opioids have limited benefit and can cause substantial adverse effects.

Short-term intra-articular corticosteroids can provide relief during an inflammatory exacerbation, although benefits usually diminish after several weeks. Their use does not exclude subsequent consideration of other injectable treatments, but repeated injections require reassessment of the diagnosis and mechanical causes of pain. A patient with an atypical presentation, inflammatory features, locking, recent trauma, or disproportionate night pain should be evaluated before receiving any infiltration.

Ácido hialurónico intraarticular: beneficio, indicación y seguridad

El ácido hialurónico forma parte del líquido sinovial y participa en la lubricación y las propiedades viscoelásticas. La hipótesis biológica suggests that intra-articular administration may improve the local environment and reduce nociceptive signaling. However, injected formulations differ in molecular weight, concentration, cross-linking, and viscosity, and these characteristics have not consistently predicted clinical outcomes. Restoration of the original cartilage matrix has not been demonstrated.

Systematic reviews and meta-analyses generally describe a small symptomatic benefit for knee osteoarthritis, especially in pain, with functional changes usually less pronounced. The average difference in pain across studies often amounts to only a few points on scales such as WOMAC, and its clinical relevance varies according to baseline severity and the minimum important difference used. At longer follow-up, confidence intervals frequently include no meaningful difference. Benefits appear somewhat greater when placebo injections or usual care are used as comparators, which highlights the importance of the study design.

The major guidelines do not give a uniform answer. EULAR recommended in 2019 that intra-articular hyaluronic acid be considered for knee osteoarthritis, conditionally and usually as a later therapeutic step. OARSI also considered it appropriate for the knee, while maintaining that this did not imply a structural or disease-modifying effect. In contrast, NICE advises against offering intra-articular hyaluronan for osteoarthritis, and the American College of Physicians recommends against it. The American Academy of Orthopaedic Surgeons judged in 2021 that it may reduce pain and improve function, although the strength of that recommendation was moderate.

Adverse effects are usually local and transient, including pain, swelling, and injection-site reactions. Hypersensitivity is uncommon. As with any joint injection, aseptic technique is essential, and active infection, cellulitis, or suspected septic arthritis constitute clear reasons to defer the procedure. If there is a substantial effusion, aspiration and analysis may be appropriate before treatment. Products should be selected according to regulatory approval and local guidance, avoiding assumptions that all formulations, repeat regimens, or high-molecular-weight products are interchangeable.

Plasma rico en plaquetas: resultados e incertidumbre

El plasma rico en plaquetas se obtiene by concentrating platelets from autologous blood. Its theoretical appeal rests on the release of growth factors and mediators that may influence inflammation and tissue repair. In practice, preparations vary substantially in platelet concentration, leukocyte content, activation method, additives, injection volume, and number of sessions. Labels such as “plasma rico en plaquetas” do not identify a single standardized intervention, which makes comparisons between trials particularly difficult.

Evidence from randomized trials and systematic reviews points toward possible short-term improvements in pain and function when plasma rico en plaquetas is compared with placebo or usual care. The size and duration of that benefit remain uncertain, with some pooled analyses finding clinically relevant differences and others concluding that the benefit is small or absent at six months. Studies frequently have small samples, variable diagnostic criteria, and incomplete reporting of treatment protocols, so the certainty of the evidence is generally low.

Some head-to-head trials suggest better pain outcomes than hyaluronic acid at six or twelve months. Other studies find no clear difference, and methodological limitations reduce confidence in any claim of superiority. The route of administration also matters: intra-articular, ultrasound-guided, and peripheral injections cannot be treated as equivalent. Imaging studies have not provided consistent evidence of cartilage regeneration, joint-space restoration, or slower structural progression.

Because the product is autologous, allergic reactions to the plasma itself are exceptionally unlikely. Pain, bruising, bleeding, swelling, and transient increases in inflammatory symptoms are more common, while infection remains rare but possible. Thrombocytopenia, significant coagulopathy, anticoagulant treatment, skin infection, or systemic infection require an individualized risk assessment. Cost, availability, regulatory status, and the need for repeated sessions also influence whether plasma rico en plaquetas can be offered appropriately in primary care.

Cómo interpretar las discrepancias entre guías

The apparent contradiction among recommendations often reflects different questions, evidence windows, and methods for evaluating benefit. GRADE separates the certainty of evidence from the strength of a recommendation. A conditional recommendation can be issued with low-certainty evidence when benefits may exceed harms for selected patients, whereas a strong recommendation against an intervention may follow when controlled trials show little added value. EULAR, OARSI, NICE, ACP, and AAOS also differ in how they weigh patient preferences, resource use, product regulation, and the distinction between statistical and clinical importance.

Direct comparisons should not be interpreted as a simple ranking of techniques. Hyaluronic acid may be less expensive, more widely available, and easier to administer, while plasma rico en plaquetas may involve greater costs and complexity. A trial showing an advantage at six months does not establish superiority at two years or demonstrate prevention of joint replacement. Combining sequential treatments has also been studied, but evidence for repeated hyaluronic acid followed by platelet injections, or the reverse, remains insufficient to support a routine sequence.

Patient selection should focus on clinically relevant factors: symptom pattern, functional demands, previous response, comorbidity, contraindications, treatment burden, and expectations. Radiographic severity alone has not been validated as a reliable predictor of response, just as the absence of radiographs should not prevent treatment in a clinically typical case. A person seeking a definitive cure is poorly served by either infiltration, while a patient with persistent, disabling symptoms who understands the uncertain benefit may reasonably consider a carefully monitored trial.

Aplicación práctica de las decisiones

A practical pathway begins by confirming the clinical diagnosis and ensuring that exercise, self-management, weight interventions where indicated, and appropriate medication have been attempted. Before an injection, record baseline pain and function using a validated measure, define a meaningful therapeutic target, and discuss alternatives. For hyaluronic acid, document the exact product, regimen, and local recommendation. For plasma rico en plaquetas, explain the preparation, expected uncertainty, number of sessions, cost, and lack of proven disease-modifying effect.

A reassessment should be scheduled after an adequate trial, often at six to eight weeks and again at three to six months. Repeated treatment is difficult to justify without a reproducible benefit from the first course. If symptoms do not improve, reconsider the diagnosis, mechanical factors, adherence to conservative care, and the original treatment goal rather than continuing infiltrations by default. Shared decision-making should also establish in advance when the intervention will be stopped.

Para llevar esta revisión a la consulta, incorpore una ficha de decisión compartida, documente el producto y el protocolo utilizados y mida la respuesta con una misma escala. Priorice siempre el tratamiento conservador como eje, reserve las infiltraciones para casos seleccionados y mantenga una vigilancia predefinida del beneficio clínico.