Introduction: The Overlooked Joint
When patients present with knee pain, the conversation typically centres on the familiar image of bone-on-bone arthritis affecting the main weight-bearing surfaces of the knee. However, this narrative overlooks a critical and frequently misdiagnosed source of knee osteoarthritis: the patellofemoral joint. This smaller articulation, where your kneecap glides against the front of your thigh bone, represents a distinct compartment with its own patterns of degeneration, symptom profile, and treatment requirements.
The patellofemoral joint is formed by the posterior surface of the patella (kneecap) and the trochlear groove of the femur—a shallow channel at the front of the lower thighbone. During knee movement, your kneecap travels through this groove, distributing forces from your powerful quadriceps muscle across the joint surface. When osteoarthritis develops here, it creates a pattern of symptoms quite different from the more commonly discussed tibiofemoral arthritis.
Research by Stefanik and colleagues published in Osteoarthritis and Cartilage demonstrated that approximately 24% of knee osteoarthritis cases involve isolated patellofemoral disease, with no significant changes in the tibiofemoral compartment (Stefanik et al., 2011). This represents nearly a quarter of all knee OA patients whose condition may be misattributed or inadequately addressed by treatments designed for the main knee joint. When combined patellofemoral and tibiofemoral disease is included, the patellofemoral compartment is involved in over 65% of symptomatic knee osteoarthritis cases (Duncan et al., 2006).
The clinical significance of this distinction cannot be overstated. Patellofemoral osteoarthritis responds to different interventions, is provoked by different activities, and requires specific rehabilitation strategies that target the unique biomechanics of patellar tracking. For a comprehensive understanding of knee osteoarthritis in general, our complete guide to knee osteoarthritis provides essential background information that complements the specialised focus of this article.
Anatomy of the Patellofemoral Joint
The Patella: Structure and Function
The patella is the largest sesamoid bone in the human body—a bone that develops within a tendon. Embedded in the quadriceps tendon superiorly and connected to the tibial tuberosity via the patellar tendon inferiorly, it serves as a crucial biomechanical lever. By increasing the moment arm of the quadriceps muscle, the patella enhances the efficiency of knee extension by approximately 50%, meaning your quadriceps would need to generate substantially more force without it (Grelsamer and Weinstein, 2001).
The posterior surface of the patella is divided into medial and lateral facets by a central vertical ridge. These facets are covered by articular cartilage that is uniquely thick—measuring 6 to 7 millimetres in healthy adults. This represents the thickest articular cartilage anywhere in the human body, reflecting the enormous compressive forces this joint must withstand. During deep squatting, patellofemoral joint reaction forces can exceed seven times body weight (Wallace et al., 2002).
The Trochlear Groove
The femoral trochlea forms the opposing surface of the patellofemoral joint. This saddle-shaped groove at the anterior aspect of the distal femur provides the track through which the patella glides during knee flexion and extension. The depth and geometry of the trochlear groove vary considerably between individuals, and these variations significantly influence patellar stability and the distribution of contact stresses across the joint surface.
A shallow or dysplastic trochlea—a congenital variation present in approximately 2-3% of the population—predisposes to patellar instability and, subsequently, to accelerated cartilage wear (Dejour et al., 1994). Understanding trochlear geometry is therefore essential when assessing patellofemoral problems.
Patellar Tracking Mechanics
As the knee moves from full extension into flexion, the patella follows a complex three-dimensional path. In full extension, the patella sits above the trochlea with minimal bony constraint. As flexion begins, the patella engages the trochlear groove, initially making contact via its inferior pole and lateral facet. With deeper flexion, contact progresses superiorly along the patellar surface, while the contact area shifts from lateral to more central, and eventually the medial facet engages with the trochlea.
This tracking pattern is controlled by a balance of forces: the quadriceps pulling superiorly, the patellar tendon pulling inferiorly, and the medial and lateral retinacular structures providing side-to-side restraint. Any imbalance in these forces leads to abnormal tracking, concentrated contact stresses, and accelerated cartilage degeneration.
The Q-Angle Concept
The Q-angle (quadriceps angle) is formed by a line from the anterior superior iliac spine to the centre of the patella, and a second line from the centre of the patella to the tibial tuberosity. This angle reflects the lateral pull vector of the quadriceps on the patella. Normal values typically range from 10-15 degrees in men and 15-20 degrees in women, with the difference attributable to the relatively wider pelvis in females.
An increased Q-angle creates a greater laterally directed force on the patella during quadriceps contraction, increasing the load on the lateral patellar facet and its corresponding trochlear surface. This biomechanical disadvantage represents one of several factors contributing to the higher prevalence of patellofemoral problems in women (Powers, 2003).
How Patellofemoral Osteoarthritis Develops
The pathogenesis of patellofemoral osteoarthritis involves a complex interplay of anatomical, biomechanical, and biological factors. Understanding these mechanisms is essential for developing effective prevention and treatment strategies.
Malalignment and Abnormal Tracking
Lateral patellar tilt—where the patella is oriented with its lateral edge tilted posteriorly into the trochlea—creates concentrated stress on the lateral facet. This tilt is often accompanied by lateral patellar displacement, where the entire patella sits too far laterally within or outside the trochlear groove. Both conditions result from an imbalance between tight lateral structures (the lateral retinaculum and iliotibial band) and weak or inhibited medial structures (the vastus medialis obliquus and medial retinaculum).
Increased Q-angle, whether from anatomical variations (femoral anteversion, external tibial torsion, foot pronation) or functional factors (hip weakness, altered gait patterns), compounds the lateral tracking tendency. Over time, the persistently overloaded lateral compartment undergoes cartilage breakdown, subchondral bone changes, and eventually frank osteoarthritis.
Vastus Medialis Obliquus (VMO) Weakness
The VMO is the only dynamic medial stabiliser of the patella. Its fibres run at an oblique angle (approximately 50-55 degrees to the femoral axis) and insert directly into the medial patellar border. When the VMO contracts effectively, it counteracts the lateral pull of the vastus lateralis and maintains central patellar tracking.
However, the VMO is exquisitely sensitive to joint effusion, pain, and inflammation. Even small amounts of swelling trigger reflex inhibition of this muscle—a phenomenon termed arthrogenic muscle inhibition (Rice and McNair, 2010). Once inhibited, the VMO atrophies rapidly, creating a self-perpetuating cycle: lateral tracking causes cartilage damage and inflammation, which inhibits the VMO, which worsens lateral tracking, which accelerates cartilage damage.
Trochlear Dysplasia
Developmental variations in trochlear geometry create mechanical environments predisposing to patellofemoral degeneration. A shallow trochlea provides inadequate bony constraint to the patella, allowing abnormal movement and instability. A flat or convex trochlea (rather than the normal concave shape) represents severe dysplasia associated with recurrent patellar dislocations and early-onset osteoarthritis.
Research has demonstrated that individuals with trochlear dysplasia show accelerated cartilage loss compared to those with normal trochlear geometry, even in the absence of frank instability episodes (Stefanik et al., 2012).
Trauma and Repetitive Loading
Direct trauma to the anterior knee—from falls, motor vehicle accidents, or sports injuries—can damage the articular cartilage directly, initiating a degenerative cascade. Patellar dislocation or subluxation events cause shear forces that strip cartilage from the bone surface, with chondral or osteochondral fragments sometimes remaining as loose bodies within the joint.
Even without acute injury, repetitive loading in flexed positions accelerates patellofemoral wear. Occupations requiring frequent squatting, kneeling, or stair climbing impose millions of high-force cycles on the patellofemoral joint over a working lifetime. This explains the increased prevalence of patellofemoral osteoarthritis in certain occupational groups and in athletes whose sports demand repeated deep knee flexion.
How Patellofemoral OA Differs from Tibiofemoral OA
Distinguishing patellofemoral from tibiofemoral osteoarthritis has profound implications for treatment selection and prognosis. These conditions share some features but differ substantially in their clinical presentation.
Symptom Location and Character
Patellofemoral osteoarthritis characteristically produces anterior knee pain—around, behind, or beneath the kneecap. Patients often struggle to localise the discomfort precisely, describing it as a diffuse ache across the front of the knee. In contrast, tibiofemoral osteoarthritis typically produces pain along the medial or lateral joint line, corresponding to the affected compartment.
The quality of pain also differs. Patellofemoral pain often has a grinding or crunching quality (crepitus), noticeable when the kneecap moves under load. Patients may report the sensation of the kneecap "catching" or feeling unstable, particularly when descending stairs or hills.
Provocative Activities
The activities that worsen patellofemoral osteoarthritis relate directly to the biomechanics of this joint. Stair climbing (particularly descent), squatting, kneeling, and rising from seated positions all increase patellofemoral joint reaction forces and typically reproduce symptoms.
Perhaps most distinctive is the "theatre sign"—pain that develops after prolonged sitting with the knees flexed, as when watching a film or travelling in a car. In this position, the patella is compressed against the trochlea for extended periods, provoking discomfort that resolves with standing and moving. This contrasts with tibiofemoral arthritis, where symptoms are typically worse with walking and weight-bearing activities and improve with rest.
Clinical Examination Findings
Physical examination reveals characteristic findings in patellofemoral disease. Peripatellar tenderness—pain on palpation of the patellar margins, particularly the medial and lateral borders—is common. The patellar grind test (or Clarke's sign), where downward pressure on the patella during quadriceps contraction reproduces pain, suggests retropatellar cartilage pathology.
Assessment of patellar tracking often reveals lateral deviation during active knee extension, sometimes with a "J-sign"—lateral movement of the patella at terminal extension. Palpating the patella during passive knee flexion and extension may reveal crepitus correlating with cartilage damage.
In contrast, tibiofemoral osteoarthritis produces tenderness along the joint line itself, often with palpable osteophytes at the femoral condyles. Varus or valgus stress testing may reproduce pain, and there may be ligamentous laxity secondary to bone loss.
Diagnosis of Patellofemoral Osteoarthritis
Accurate diagnosis of patellofemoral osteoarthritis requires appropriate imaging and clinical assessment techniques that specifically evaluate this compartment.
Imaging Studies
Standard anteroposterior and lateral knee radiographs often fail to visualise patellofemoral pathology adequately. The skyline view (also called the Merchant view, taken with the knee flexed to 45 degrees) is essential for assessing the patellofemoral compartment. This tangential projection reveals joint space narrowing, osteophyte formation, subchondral sclerosis, and patellar tilt or subluxation.
Computed tomography (CT) scanning provides superior bone detail and is particularly valuable for assessing trochlear geometry, including measurements such as the trochlear depth, sulcus angle, and lateral trochlear inclination. CT can identify bony abnormalities contributing to patellar instability and maltracking.
Magnetic resonance imaging (MRI) offers excellent soft tissue visualisation, including direct assessment of articular cartilage thickness and integrity. MRI can detect early cartilage changes before they become apparent on radiographs, potentially identifying patients who might benefit from preventive interventions. It also reveals associated pathology such as synovitis, bone marrow lesions, and lateral retinacular tightness.
Clinical Tests
Beyond the patellar grind test mentioned earlier, several clinical assessments help establish the diagnosis. Observation of patellar tracking during active knee extension reveals abnormal lateral movement or tilting. The patellar tilt test assesses whether the patella can be tilted to a neutral position; inability to do so suggests lateral retinacular tightness.
At Bruno Physical Rehabilitation, we employ Infrared Thermography as an objective tool for monitoring periarticular inflammation around the patellofemoral joint. This imaging modality detects heat distribution patterns that correlate with synovitis and capsular inflammation, providing both diagnostic information and a means to track treatment response over time. Thermal asymmetries between the affected and unaffected knees offer quantifiable data supporting clinical decision-making.
Our comprehensive Biomechanical Assessment protocol includes 3D gait analysis and force platform testing to identify dynamic factors contributing to abnormal patellar loading. Single-leg loading tests reveal hip weakness or trunk control deficits that increase patellofemoral stress. This assessment extends beyond the knee to evaluate the entire lower limb kinetic chain, including foot mechanics and hip function.
The VMO Connection: Why This Muscle Matters
The vastus medialis obliquus deserves special attention in any discussion of patellofemoral pathology. This muscle represents the primary dynamic defence against lateral patellar tracking, and its dysfunction is both a consequence and a perpetuator of patellofemoral osteoarthritis.
Anatomy and Function
The VMO is the most distal portion of the vastus medialis muscle, distinguished by its oblique fibre orientation. While the proximal vastus medialis fibres run nearly parallel to the femoral shaft (at approximately 15-18 degrees), the VMO fibres angle at 50-55 degrees, providing a significant medial vector when they contract. The VMO inserts directly into the medial patellar border and the medial patellofemoral ligament, making it uniquely positioned to resist lateral patellar forces.
Research has demonstrated that the VMO activates in proportion to the laterally-directed force on the patella, suggesting a specific stabilising role rather than simple knee extension contribution (Neptune et al., 2000). When the VMO fails to activate appropriately, the unopposed pull of the vastus lateralis draws the patella laterally, increasing lateral facet pressure.
Arthrogenic Muscle Inhibition
Joint effusion, pain, and inflammation trigger reflex inhibition of the quadriceps, but the VMO is disproportionately affected. Research by Slemenda and colleagues demonstrated that quadriceps weakness—particularly VMO weakness—precedes the development of knee osteoarthritis and predicts disease progression (Slemenda et al., 1997). This finding suggests that muscle dysfunction may be a cause, not merely a consequence, of joint degeneration.
Once established, arthrogenic inhibition creates a formidable rehabilitation challenge. The neural pathways that would normally activate the VMO are suppressed at a spinal level, meaning that voluntary effort alone often fails to engage the muscle adequately. Patients attempting quadriceps exercises may simply recruit the vastus lateralis more strongly, potentially worsening their patellar tracking problem (Rice and McNair, 2010).
Why VMO Activation Requires Specific Techniques
The selective inhibition of the VMO explains why general quadriceps strengthening exercises frequently fail in patellofemoral rehabilitation. Exercises like leg press or open-chain knee extension may strengthen the quadriceps overall while leaving the VMO relatively underactivated. The resulting muscle imbalance can perpetuate abnormal patellar tracking despite apparent gains in strength.
Effective VMO rehabilitation requires techniques that either bypass neural inhibition or specifically target the VMO's activation patterns. This is where advanced technologies like neuromuscular electrical stimulation become invaluable—they can activate muscle fibres directly, overcoming the inhibitory reflexes that prevent voluntary recruitment.
Evidence-Based Treatment Strategies
Management of patellofemoral osteoarthritis requires a multimodal approach addressing pain, inflammation, muscle dysfunction, and biomechanical abnormalities. The evidence base supports several interventions when applied appropriately and in combination.
VMO-Targeted Strengthening
Research by Witvrouw and colleagues demonstrated that closed kinetic chain exercises targeting the VMO produce superior outcomes in patellofemoral pain compared to open chain exercises (Witvrouw et al., 2004). Specific exercises include:
- Terminal knee extension: From a slightly flexed position (20-30 degrees), extending the knee fully against resistance activates the VMO preferentially while minimising patellofemoral joint reaction forces
- Step-down exercises: Controlled eccentric lowering on a step emphasises VMO activation while training functional movement patterns
- Short-arc quadriceps: Extending the knee through the final 20-30 degrees of range provides VMO activation with minimal patellofemoral stress
- Mini-squats with medial emphasis: Squatting to 30-40 degrees with attention to preventing knee valgus trains integrated VMO function
The key principle is maintaining knee flexion angles below 60 degrees, where patellofemoral forces remain relatively low. Deep squats and lunges may be counterproductive in early rehabilitation, though they may be reintroduced as symptoms allow.
ALCE Neuromuscular Electrostimulation
When arthrogenic inhibition prevents adequate voluntary VMO activation, ALCE Neuromuscular Electrostimulation provides a direct solution. This advanced technology specifically targets the Type 2B (fast-twitch glycolytic) muscle fibres that are essential for explosive joint protection but which atrophy rapidly with pain and disuse.
Type 2B fibres are particularly important for several reasons:
- They generate rapid, powerful contractions necessary for dynamic joint stabilisation
- They respond to threatening situations (such as unexpected perturbations) before slower fibres can activate
- They are almost impossible to recruit voluntarily when arthrogenic inhibition is present
- They atrophy at roughly twice the rate of Type 1 fibres during disuse
The ALCE system uses carrier frequencies up to 1 MHz in some modalities, with burst frequencies of 75-100 Hz specifically calibrated for Type 2B recruitment. This approach bypasses the inhibited neural pathways, directly activating muscle fibres that the patient cannot recruit voluntarily. Over successive sessions, this reverses arthrogenic inhibition, rebuilds muscle volume, and restores the protective capacity of the quadriceps.
For patients aiming to return to sport, gym training, or physically demanding daily activities, this technology is often essential. Without restoring Type 2B function, patients may regain some strength but remain unable to generate the rapid protective contractions needed for high-level activities.
MLS Laser Therapy
Inflammation within and around the patellofemoral joint contributes significantly to pain and perpetuates the cycle of inhibition and degeneration. MLS (Multiwave Locked System) Laser Therapy addresses this through synchronised dual-wavelength emission at 808nm and 905nm, providing anti-inflammatory, analgesic, and biostimulatory effects simultaneously.
A systematic review and meta-analysis published in BMJ Open confirmed the efficacy of photobiomodulation therapy for knee osteoarthritis, demonstrating significant improvements in pain and function compared to placebo (Stausholm et al., 2019). MLS therapy specifically targets retropatellar synovitis—inflammation of the synovial lining behind the kneecap—and periarticular soft tissue inflammation affecting the retinacula, fat pads, and peritendinous structures.
This modality is particularly valuable because it provides anti-inflammatory benefits without the systemic effects or gastrointestinal risks associated with non-steroidal anti-inflammatory medications. For patients with contraindications to oral anti-inflammatories, or those seeking to minimise medication use, MLS Laser Therapy offers an evidence-based alternative.
Patellar Taping
The McConnell patellar taping technique, developed by Australian physiotherapist Jenny McConnell, aims to correct abnormal patellar positioning by applying adhesive tape in specific configurations. The tape creates a mechanical correction of lateral tilt or displacement, and may also enhance proprioceptive feedback from the knee.
Research by Crossley and colleagues demonstrated that patellar taping combined with exercise produces greater improvements in pain and function than exercise alone in patellofemoral pain syndrome (Crossley et al., 2002). While the mechanism of benefit remains debated—with some evidence suggesting that even placebo taping produces effects—the clinical utility of taping as an adjunct to exercise therapy is well-established.
Taping can be particularly valuable during the initial phases of rehabilitation, reducing pain sufficiently to allow effective exercise participation. As VMO strength improves and dynamic control develops, dependence on taping typically decreases.
Biomechanical Assessment and Correction
The patella does not function in isolation—its position and loading are influenced by structures from the foot to the hip. Comprehensive Biomechanical Assessment identifies contributing factors throughout the kinetic chain:
- Foot pronation: Excessive foot pronation causes internal rotation of the tibia, which increases the functional Q-angle and promotes lateral patellar tracking. This mechanism explains why addressing foot mechanics often improves patellofemoral symptoms (Powers, 2003)
- Hip abductor weakness: Weakness of the gluteus medius and minimus allows the pelvis to drop and the femur to adduct and internally rotate during single-leg stance. This creates a dynamic increase in knee valgus and Q-angle, loading the lateral patellofemoral compartment
- Hip external rotator weakness: Similarly, weak external rotators allow femoral internal rotation during activities, contributing to abnormal patellofemoral mechanics
Our assessment incorporates 3D gait analysis, force platform testing, and single-leg loading assessments to quantify these factors objectively. Treatment then addresses identified deficits through targeted strengthening, movement retraining, and where appropriate, orthotic intervention.
Therapeutic Ultrasound
Therapeutic Ultrasound at 1 MHz provides optimal treatment depth for knee structures, reaching 3-5cm to affect the patellar tendon, retinacular structures, and periarticular tissues. Both thermal and non-thermal effects contribute to clinical benefit.
Thermal effects include increased tissue extensibility, enhanced blood flow, and pain modulation. Non-thermal effects, particularly acoustic streaming and cavitation, influence cellular processes including collagen synthesis and inflammatory mediator release. Applied before exercise, therapeutic ultrasound improves capsular and retinacular extensibility, facilitating more effective movement and strengthening.
This modality is particularly valuable for addressing lateral retinacular tightness—a common finding in patellofemoral problems—and for managing patellar tendon irritation that frequently accompanies patellofemoral osteoarthritis.
TENS for Pain Management
TENS (Transcutaneous Electrical Nerve Stimulation) provides effective pain modulation through the gate control mechanism first described by Melzack and Wall (1965). High-frequency TENS at 80-120 Hz activates large-diameter sensory nerve fibres that inhibit pain transmission at the spinal cord level, providing immediate analgesic effects.
This pain relief is strategically valuable in rehabilitation: by reducing pain during and after exercise sessions, TENS enables patients to participate in therapeutic activities that would otherwise be intolerable. Pain control also reduces arthrogenic inhibition, facilitating better muscle activation during strengthening exercises.
Infrared Thermography for Treatment Monitoring
Infrared Thermography provides objective monitoring of inflammatory status throughout the treatment programme. By comparing heat distribution patterns before and after individual treatment sessions, and tracking changes over the course of rehabilitation, we can quantify treatment response and adjust interventions accordingly.
This technology is particularly valuable for patients with subclinical inflammation—those whose joints appear clinically unremarkable but who demonstrate thermal asymmetries suggesting ongoing inflammatory activity. Identifying and addressing this hidden inflammation may prevent progression and improve long-term outcomes.
Activity Modification versus Avoidance
A common mistake in managing patellofemoral osteoarthritis is complete avoidance of activities that load the joint. While this strategy reduces symptoms in the short term, it leads to progressive deconditioning, muscle atrophy, weight gain, and ultimately worse long-term outcomes.
The appropriate approach is activity modification—adjusting how activities are performed rather than eliminating them entirely. Examples include:
- Using the handrail when climbing stairs to reduce patellofemoral load
- Rising from chairs using armrests to assist
- Limiting deep squatting while maintaining partial-range squatting exercises
- Breaking prolonged sitting into shorter periods with movement breaks
- Cycling rather than running for cardiovascular exercise (lower patellofemoral forces)
The goal is maintaining activity levels sufficient to preserve muscle function, cardiovascular fitness, and mental wellbeing while allowing inflamed joint structures to recover. As rehabilitation progresses and joint status improves, restrictions can be progressively lifted.
The Hip and Foot Chain
Research consistently demonstrates that patellofemoral problems often originate from dysfunctions above or below the knee. A narrow focus on the patellofemoral joint itself frequently misses the underlying causes of abnormal patellar loading.
Hip Contributions
The hip musculature exerts profound influence on knee mechanics during functional activities. During single-leg stance—which occurs with every walking step, stair climb, or running stride—the hip abductors must prevent pelvic drop on the unsupported side. When these muscles are weak, the pelvis drops, creating a functional knee valgus position that increases lateral patellofemoral loading.
Similarly, hip external rotator weakness allows the femur to internally rotate, again increasing the effective Q-angle and promoting lateral patellar tracking. Research by Powers and colleagues demonstrated that patients with patellofemoral pain show reduced hip abductor and external rotator strength compared to asymptomatic controls (Powers, 2010).
Treatment addressing hip weakness produces significant improvements in patellofemoral symptoms, often exceeding the benefits of knee-focused interventions alone. This finding has fundamentally changed rehabilitation approaches for patellofemoral conditions.
Foot Contributions
At the distal end of the kinetic chain, foot mechanics influence patellar loading through their effect on tibial rotation. Excessive pronation (rolling inward of the foot) causes the tibia to internally rotate, which increases the Q-angle and promotes lateral patellar tracking. This mechanism is particularly relevant in individuals with pes planus (flat feet) or rearfoot valgus alignment.
Conversely, a rigid supinated foot may fail to absorb impact forces adequately, transmitting greater loads to the knee. Assessment of foot mechanics and gait patterns is therefore essential in comprehensive patellofemoral evaluation.
For more detailed information on how problems distant from the knee contribute to knee symptoms, our article on why knee pain is not always a knee problem explores these relationships in depth.
Orthotics and Bracing
External devices can contribute to patellofemoral management, though the evidence base is more limited than for exercise-based interventions.
Foot Orthoses
For patients with foot pronation contributing to their patellofemoral symptoms, custom or prefabricated foot orthoses may help by controlling rearfoot motion and reducing tibial internal rotation. Research has shown improvements in patellofemoral pain with orthotic use, though the magnitude of effect varies between studies (Collins et al., 2008).
The best evidence supports orthotic use in patients with demonstrable foot mechanics abnormalities, particularly those with delayed or excessive pronation during gait. Prescribing orthoses without biomechanical assessment is unlikely to provide optimal benefit.
Patellofemoral Bracing
Patellofemoral braces typically incorporate a patellar cutout or buttress intended to improve patellar tracking. While many patients report subjective benefit, the biomechanical evidence for these devices is mixed. Some studies suggest they may improve patellar alignment, while others find no significant mechanical effect (Warden et al., 2008).
Braces may provide benefit through proprioceptive mechanisms—enhancing awareness of knee position—rather than through direct mechanical effects. They can be useful during activity resumption, providing confidence while rehabilitation progresses, but should not replace active rehabilitation approaches.
When Surgery Is Considered
Conservative management successfully controls symptoms in the majority of patellofemoral osteoarthritis patients. However, when appropriately applied non-surgical treatment fails, several surgical options exist.
Lateral Release
Arthroscopic lateral retinacular release involves cutting the tight lateral retinaculum to reduce lateral pull on the patella. This procedure was once performed frequently but has fallen from favour as evidence accumulated showing limited long-term benefit and potential complications including medial patellar instability (Kolowich et al., 1990). It may still be appropriate in selected patients with documented lateral retinacular tightness and lateral tilt, but is now typically combined with medial stabilisation procedures.
Tibial Tubercle Osteotomy
Procedures that reposition the tibial tubercle (where the patellar tendon attaches) can alter patellar tracking and load distribution. Medialisation shifts the tubercle inward, reducing the Q-angle. Anteriorisation moves it forward, reducing patellofemoral contact pressure. The Fulkerson procedure combines these movements, achieving both medialisation and anteriorisation.
These procedures require careful patient selection and produce best results in younger patients with malalignment and focal cartilage damage, rather than in those with diffuse degenerative changes.
Patellofemoral Arthroplasty
For isolated patellofemoral osteoarthritis with preservation of the tibiofemoral compartments, partial knee replacement involving only the patellofemoral joint offers a bone-sparing alternative to total knee replacement. This procedure resurfaces the trochlea with a metal component and the patella with a polyethylene button.
Medium-term outcomes are generally favourable, with studies reporting significant improvements in pain and function (Ackroyd et al., 2007). However, progression of tibiofemoral arthritis may eventually necessitate conversion to total knee replacement in some patients.
Total Knee Replacement
When patellofemoral osteoarthritis coexists with significant tibiofemoral disease, or when patellofemoral arthroplasty has failed, total knee replacement addresses