Patellofemoral conditions

The patellofemoral joint is where the kneecap meets the groove at the end of the thigh bone. Problems here fall into two groups that are assessed differently: pain around or behind the kneecap, brought on by activities that load a bent knee, and instability, where the kneecap slips or dislocates out of its groove. The two can overlap, but the distinction shapes the whole assessment.

Symptoms

  • Pain around or behind the kneecap, brought on by squatting, stairs, running, or sitting for long periods with the knee bent.
  • Grinding or a grating sensation at the front of the knee on bending.
  • A sense of the kneecap slipping sideways or giving way — and, in some cases, dislocating outright.
  • Aching that builds after activity, rather than a sharp pain at a particular moment.
How patellofemoral problems develop

Patellofemoral pain typically builds up rather than starting with an injury, and often follows a change in load — more running, a return to sport after a break, a new job spent on the feet. It reflects the demand placed on the joint against what the knee, hip and trunk can control, which is why strength and movement control at the hip matter as much as at the knee. Instability is different. The kneecap is held in its groove by the shape of the groove itself and by a ligament on the inner side, and it dislocates outwards; a first dislocation almost always tears that ligament. Whether it recurs depends heavily on anatomy — a shallow groove, a kneecap that sits high, the position of the tibial tubercle, and generally lax joints. With none of those factors the risk of another dislocation is low; with all of them it is high.

How it is assessed

Assessment begins with how the problem started and what the knee has done since, followed by an examination of both knees so the affected side can be compared with the other. Imaging is used where it would change what is done, rather than as a matter of routine.

In clinic

For pain, the examination reproduces the symptoms by loading the bent knee, checks tenderness around the edges of the kneecap and for an effusion, and assesses hip, quadriceps and trunk control along with how the knee moves in a single-leg squat. For instability, it assesses how far the kneecap can be moved sideways and whether doing so reproduces the feeling of it dislocating, how the kneecap tracks as the knee straightens, and whether the joints are generally lax. The alignment and rotation of the whole limb are looked at in both.

Imaging

Imaging is not needed to diagnose patellofemoral pain, which is a clinical diagnosis. It is used where instability is the problem, or where another diagnosis is possible: X-rays show the shape of the groove and the height of the kneecap, and MRI or CT shows the ligament on the inner side, damage to the cartilage surfaces, and the measurements used to judge whether anatomy is driving the instability.

Stage and severity

These conditions are described by the pattern of symptoms and by what is contributing to them.

Pattern of symptoms
Whether the problem is pain alone, a sense of the kneecap slipping without it leaving the groove, or frank dislocation. This is the distinction that shapes treatment.
Contributing factors
The shape of the trochlear groove, the height and tracking of the kneecap, the rotation and alignment of the limb, generalised ligament laxity, and the strength and control of the hip and quadriceps. Several usually apply together, and the more that do, the higher the risk of recurrence.
With other conditions
Damage to the cartilage at the back of the kneecap or in the groove, a loose fragment after a dislocation, or established patellofemoral osteoarthritis. Each changes what treatment is aiming at.
Associated conditions

A kneecap dislocation frequently damages cartilage — at the back of the kneecap, on the outer edge of the femoral groove, or both — and can leave a loose fragment in the joint, which is one reason a first dislocation is worth imaging rather than simply resting. Persistent patellofemoral pain in a younger person is associated with patellofemoral osteoarthritis in later life, and pain here often sits alongside other sources of pain at the front of the knee, including tendon problems. Because the joint is loaded by the whole limb, the hip and the foot are examined even when the symptoms are entirely at the knee.

Treatment options

The two options below are set out side by side. Which applies depends on the findings, the structures involved and what you need to return to.

Non-surgical care

What it involves
A supervised exercise programme combining knee and hip strengthening, which is the treatment with the strongest evidence behind it. Load management, and — as additions to exercise rather than substitutes for it — taping, bracing or foot orthoses where they help someone exercise comfortably.
Typical course
Exercise over a period of months. Improvement is gradual, and consistency matters more than intensity.
Considerations
First-line for patellofemoral pain, and the usual first treatment after a first-time dislocation where there is no loose fragment. Manual therapy on its own is not recommended; combined programmes do better than single interventions.
Follow-up
Reviewed as the programme progresses, with imaging or a change of plan reconsidered if symptoms do not settle.

Surgical treatment

What it involves
For recurrent instability, reconstruction of the ligament on the inner side of the kneecap, with correction of the underlying anatomy — moving the tibial tubercle, or reshaping the groove — where the measurements call for it. For cartilage damage or a loose fragment, arthroscopic treatment of that lesion.
Typical course
Movement is restored early after ligament reconstruction, with strengthening over the following months and return to sport typically at around six months. Bony procedures need longer protection.
Considerations
Reserved for recurrent dislocation, for a fragment of cartilage or bone displaced by a dislocation, or for a specific structural problem identified on examination and imaging. Surgery has no established role in patellofemoral pain without instability, where the evidence supports exercise.
Follow-up
Reviewed through rehabilitation and again before return to sport.

What recovery involves

Recovery depends on which treatment is used. The stages below apply to surgery for instability, and the timings are typical rather than fixed — progress is judged on what the knee can do at each stage.

  1. Early recovery

    The first two weeks

    Settle swelling, protect the reconstruction in a brace as directed, and begin regaining movement and quadriceps activation.

  2. Movement and control

    Weeks 2 to 6

    Full range of movement, normal walking, and early strengthening of the quadriceps and hip.

  3. Strength

    Weeks 6 to 16

    Progressive strengthening, single-leg control, and a return to running when the knee allows.

  4. Return to sport

    From around six months

    Agility and sport-specific training, with strength and confidence in the kneecap tested before full return.

Page information

Reviewed by
Dr Lai Kah Weng
Version
1.0
Review date
September 2026
Next review
September 2027

References

  1. Crossley KM, Stefanik JJ, Selfe J, et al. 2016 patellofemoral pain consensus statement from the 4th International Patellofemoral Pain Research Retreat, Manchester. Part 1: terminology, definitions, clinical examination, natural history, patellofemoral osteoarthritis and patient-reported outcome measures. Br J Sports Med. 2016;50(14):839–843.
  2. Collins NJ, Barton CJ, van Middelkoop M, et al. 2018 consensus statement on exercise therapy and physical interventions (orthoses, taping and manual therapy) to treat patellofemoral pain: recommendations from the 5th International Patellofemoral Pain Research Retreat, Gold Coast, Australia, 2017. Br J Sports Med. 2018;52(18):1170–1178.
  3. Jaquith BP, Parikh SN. Predictors of recurrent patellar instability in children and adolescents after first-time dislocation. J Pediatr Orthop. 2017;37(7):484–490.

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