Patellofemoral instability (2026)

Frequent injuries in active under 18s (up to 5.8 per 100,000) with an increased risk in adolescent females (29 in 100,000) (Bailey, 2021; Blønd, 2024; Garrett, 2021; Pauyo, 2022).

First time patellar dislocation (FTPD) is uncommon in adults older than 25 (Blønd, 2024).

Rate of recurrence is 17-33% and for those with recurrent dislocations the risk of re-dislocation is over 50% (Pauyo, 2022).

Lateral instability accounts for 95% of patellofemoral instability (PFI) and almost always has identifiable anatomic risk factors. (Pauyo, 2022).

Medial instability is often due to a direct trauma or iatrogenic cause (Pauyo, 2022).

Patellar instability definition:

“Symptomatic deficiency of the passive constraint such that the patella may escape partially or completely from its asymptomatic position with respect to the femoral trochlea under the influence of displacing force. Such displacing force could be generated by muscle tension, movement, and/or externally applied forces.” (Post, 2018).

There are two broad types of patellofemoral instability (PFI)

• PFI with a history of trauma

• Non-traumatic PFI where dislocations occur with regular daily activities or non-contact sports (Pauyo, 2022).

Patients may describe a sensation of instability or previous subluxations or dislocations and knee effusion. (Pauyo, 2022).

They may have difficulty weight bearing, straightening the affected knee and may report instability while walking, using stairs, running or jumping (Pauyo, 2022).

Acute Presentation

Examination may be limited in the acute presentation due to pain, swelling and patient anxiety (Blønd, 2024).

Post (2018) suggests assessment should include:

• general knee ROM

• patellar glide

• patellar apprehension

• palpation for tenderness along the medial patella and MPFL

• observation of effusion (with a large effusion raising suspicion for osteochondral fractures).

• assessment of alignment, hypermobility and ACL/MCL/meniscus/neuro as required.

Non-acute Presentation

Assessment in a non-acute presentation should include:

• formal assessment of generalised ligamentous laxity with a Beighton’s score

• assessment of alignment and biomechanics in gait

• patellar tracking – is a J sign present?

• special tests including patellar glide and patellar apprehension. (Pauyo, 2022)

• standing alignment

• single leg stance/squat or step down as tolerated

• hyperalgesia (Post, 2018)

• passive patellar glide test

  • if patella glides less than ¼ of the patellar width medially, suggests lateral tightness.

  • if patella glides more than ¾ of patellar width in either direction this suggests hyperlaxity (Pauyo, 2022)

Patellar Glide Test

Lateral patellar glide test also known as Patellar Apprehension Test 

Thomas Test can also be useful to determine if muscles and soft tissues surrounding the knee are influencing patellar mobility and tracking.

Structural/Mechanical

• Trochlear dysplasia

• Patella alta

• TTG (tibial tubercle – trochlear groove) distance

• Lateral patellar tilt

• MPFL (medial patellofemoral ligament) insufficiency

• Torsional limb alignment (femoral anteversion, genu valgum) (Dietrich, 2016)

• Genu valgum

• Patellar dysplasia

• VMO atrophy/weakness

• Generalised hyperlaxity (Pauyo, 2022)

Trauma

• Predominantly sustained in non-contact situations

• Most common MOI = unbalanced individual in hip and knee flexion with tibial external rotation and valgus force. (Dewan, 2020)

These alternative terms are used somewhat interchangeably:

• Patellofemoral instability

• Patellofemoral mal-tracking

• Patellofemoral subluxation

• Patellofemoral dislocation

• Traumatic dislocation

• Instability related to bony morphology

• Instability related to generalised connective tissue laxity

• Be aware of concomitant ACL and osteochondral injuries.

• Significant swelling raises suspicion of osteochondral fracture (Post, 2018)

See Red Flags and Serious Pathology section

There is a lack of evidence to guide the content of patient education for patellar instability.

In designing a personalised treatment approach (for a future randomised controlled trial comparing personalised therapy with operative treatment for recurrent patellar dislocation), Arnold (2024) includes advice, education, and behaviour modification. Fear avoidance and maladaptive health beliefs were identified as probable targets for intervention.

No high-quality evidence available but literature suggests a 6-week to 3-month trial of non-surgical management (Pauyo, 2022)

Balcarek (2025) in their consensus guidance stated that physical therapy guided exercises are a necessary supplement in both operative and non-operative treatment.

Balcarek (2025) did also suggest that for skeletally mature patients, only those with low risk of recurrence and without chondral or osteochondral injuries should be managed conservatively.

For skeletally immature patients, recurrence rate is high, so the consensus group (Balcarek, 2025) agreed that thorough investigation to clarify the extent of predisposing factors should be carried out; and if the decision for non-operative treatment is made, strict follow up should be mandatory.

Exercise Type

Strengthening

There is agreement that exercise therapy should address the deficiencies likely to increase known risk factors for patellar dislocation, e.g. excessive femoral adduction and internal rotation, tibial rotation and foot pronation. (Balcarek, 2025)

Pauyo (2022) recommends strengthening exercises for quadriceps, core and hip abductors.

Forde (2025) developed a rehabilitation intervention for their pilot RCT exploring the feasibility of a full scale RCT exploring supervised versus self-managed rehabilitation for patients with patellar dislocation. Strengthening exercises followed exercise prescription guidelines of 1-3 sets of 8-12 reps at least 3 times per week with at least 2 minutes rest between sets. Participants were given advice on progressive overload to ensure exercise intensity was sufficient. The full RCT is yet to be conducted but both interventions were found to be acceptable to patients during the pilot RCT.

Dixit (2017) suggested that closed chain exercises are superior to open chain exercises in their ability to activate all portions of the quadriceps.

Flores et al (2023) reported that an unstructured lower limb physical therapy programme evidences similar outcomes to specific exercises.

Stretching

Stretching exercises have not been specifically addressed in the literature. However, Pauyo (2002) suggested the use of manual therapy to relieve iliotibial band (ITB) tightness. Such tightness may exacerbate factors like lateral patellar tilt, which is a known risk factor for dislocation. Therefore, it seems reasonable to incorporate stretching to target other soft tissue restrictions that may also influence patellar position/mobility.

Other

Balcarek (2025) also suggest that exercise therapy also includes motion exercises, gait re-education, functional neuromuscular control and sport specific training where appropriate.

Manual therapy to relieve ITB tightness (Pauyo, 2022)

Patellar mobilisation (Pauyo, 2022)

Insoles – No studies identified in the literature search specifically examined the use of insoles. However, given their potential to influence lower limb biomechanics and address risk factors such as excessive foot pronation, they may offer some benefit. Therefore, decisions regarding their use should be made on a case-by-case basis.

Bracing (Pauyo, 2022; Balcarek, 2025)

Chondral lesions in the patellofemoral articulation area are important prognostic factors. The severity of these correlates with the degree of persistent instability.

Patellar dislocation with low or no trauma is usually indicative of more severe underlying bony morphology abnormalities (Blønd, 2024)

If msk presentation and unclear diagnosis or not progressing as expected consider options:

• discus with peer (for band 6/7 staff) 

• senior (band 5/6/7 staff) 

• present at case review as per guidance

• consider for APP review as per guidance

Acute Presentation

Imaging (Plain x-ray + MRI or MRI alone) is required to rule out osteochondral fractures and/or bony abnormalities (usually completed at A&E).  It can also evaluate predisposing factors and skeletal maturity, thereby allowing an estimate of the risk of persistent instability. (Blønd, 2024).  The presence of haemarthoris or lipohaemarthrosis should raise suspicion of chondral lesions (Blønd, 2024), and/or other intraarticular concomitant injuries such as ACL tears.

Recurrent Dislocations

Imaging should allow for identification and quantification of any structural predisposing factors e.g. patella alta, trochlear dysplasia, MPFL integrity, alignment of tibial tuberosity to trochlear groove

Dietrich (2016) suggests that the most important imaging examinations are a true lateral radiograph and transverse CT or MR images of the knee.

From ortho ESP:

• In 1st time dislocation with a normal xray - patella relocated and no osteochondral defect

  • Rehab first . No specific need for early MRI although some of the south cons do MRI the 1st time dislocators that come through MIU

  • Escalate if failing rehab

• Recurrent dislocators

  • MRI suggested following ortho assessment as we ask for tibial tuberosity to trochlear groove distance (TT-TG distance) on MRI request.  This helps measure trochlear dysplasia etc as mentioned in imaging section to aid surgical decision

NHSGGC Patient information leaflet re: adolescent patellar dislocation

Arnold, S., Haque, A., Aujla, M., Barrows, R., Beard, D., Chandler, C., Chandler, E., Ellard, D.R., Eldridge, J. and Ferreira, M. (2024) ‘Recurrent patellar dislocation: personalised therapy or operative treatment? The REPPORT randomised trial protocol’, BMJ Open, 14(8), e090233.

Bailey, M.E.A., Metcalfe, A., Hing, C.B. and Eldridge, J. (2021) ‘Consensus guidelines for management of patellofemoral instability’, The Knee, 29, pp. 305–312.

Balcarek, P., Blønd, L., Beaufils, P., Askenberger, M., Stephen, J.M., Akmese, R., El Attal, R., Chouliaras, V., Ferrua, P., Minguell Monart, J., Pagenstert, G., Sillanpää, P., Vieira da Silva, M., Dirisamer, F. and Walawski, J. (2025) ‘Management of first-time patellar dislocation: the ESSKA 2024 formal consensus – Part 2’, Knee Surgery, Sports Traumatology, Arthroscopy, 33(12), pp. 4197–4206.

Blønd, L., Askenberger, M., Stephen, J.M., Akmese, R., Balcarek, P., El Attal, R., Chouliaras, V., Ferrua, P., Minguell Monart, J., Pagenstert, G., Sillanpää, P., Vieira da Silva, M., Walawski, J., Beaufils, P. and Dirisamer, F. (2025) ‘Management of first-time patellar dislocation: the ESSKA 2024 formal consensus – Part 1’, Knee Surgery, Sports Traumatology, Arthroscopy, 33(5), pp. 1925–1932.

Dewan, V., Webb, M.S.L., Prakash, D., Malik, A., Gella, S. and Kipps, C. (2020) ‘Patella dislocation: an online systematic video analysis of the mechanism of injury’, Knee Surgery & Related Research, 32(1), Article 24.

Dietrich, T.J., Fucentese, S.F. and Pfirrmann, C.W.A. (2016) Imaging of individual anatomical risk factors for patellar instability. Stuttgart: Thieme Medical Publishers, p. 65.

Dixit, S. and Deu, R.S. (2017) ‘Nonoperative treatment of patellar instability’, Sports Medicine & Arthroscopy Review, 25(2), pp. 72–77.

Flores, G.W., de Oliveira, D.F., Ramos, A.P.S., Sanada, L.S., Migliorini, F., Maffulli, N. and Okubo, R. (2023) ‘Conservative management following patellar dislocation: a level I systematic review’, Journal of Orthopaedic Surgery, 18(1), p. 393.

Forde, C.P., Costa, M.L., Tutton, E., Cook, J.A. and Keene, D.J. (2025) ‘Development of the rehabilitation interventions for people with an acute patellar dislocation in the Physiotherapy Rehabilitation Post Patellar Dislocation (PRePPeD) pilot randomised controlled trial’, Bone & Joint Open, 6(4), p. 469.

Garrett, B.R. and Grundill, M.L. (2021) ‘Patella dislocations and patellofemoral instability: a current concepts review’, SA Orthopaedic Journal, 20(3), pp. 167–177.

Pauyo, T., Park, J.P., Bozzo, I. and Bernstein, M. (2022) ‘Patellofemoral instability part I: evaluation and nonsurgical treatment’, JAAOS: Journal of the American Academy of Orthopaedic Surgeons, 30(22), pp. e1431–e1442.

Post, W.R. and Fithian, D.C. (2018) ‘Patellofemoral instability: a consensus statement from the AOSSM/PFF patellofemoral instability workshop’, Orthopaedic Journal of Sports Medicine, 6(1), p. 2325967117750352.