Fat Pad Injury, Fat Pad Impingement & Lateral Conflict Pain in the Knee

Fat pad injury (sometimes called fat pad impingement, Hoffa’s fat pad impingement or lateral conflict pain) is a common but often under-recognised cause of pain at the front of the knee. It can affect active people, runners, those who kneel frequently, and patients after knee injury or surgery. The pain can be sharp, catching or “pinching” around the front or outer side of the knee, especially when straightening the leg or standing for long periods.

MRI of knee fat pad impingement (Hoffa's Syndrome) with arrow pointing to the inflammation below the patella — MRI showing the location of Hoffa's Fat Pad and typical impingement zone.

Mr Simon Abram, Consultant Specialist Knee Surgeon, assesses and treats fat pad impingement and lateral conflict pain in Bath and Bristol. Care is focused on accurate diagnosis, targeted physiotherapy, and injection or keyhole surgery only where clearly beneficial.

What is the fat pad in the knee?

At the front of the knee, beneath the kneecap (patella) and patellar tendon, sits a soft structure called the infrapatellar fat pad (often known as Hoffa’s fat pad). It is richly supplied with nerves and blood vessels, and:

Helps cushion the joint
Fills the space as the knee bends and straightens
Supports smooth movement of the patellar tendon and kneecap

Because the fat pad is highly sensitive, even small areas of irritation or pinching (impingement) can cause significant pain.

What is fat pad impingement and lateral conflict pain?

Fat pad impingement occurs when part of the fat pad gets pinched between the femur (thigh bone) and the kneecap or kneecap (patella) tendon during movement. This can lead to:

Local inflammation and swelling within the fat pad
Thickening and scarring over time
Sharp “catching” pain when the knee is straightened or overloaded

Lateral conflict pain is the most common and affects the outer part of the fat pad and surrounding tissues on the outside of the kneecap. This is often linked to kneecap tracking problems, subtle alignment issues or overload in specific positions.

Causes and risk factors

Overuse or overload (running, jumping, deep squats, repeated lunges)
Direct impact or a fall onto the front of the knee
Previous knee surgery, particularly around the patellar tendon or kneecap
Patellofemoral problems (kneecap maltracking, instability or patellofemoral arthritis)
Hyperextension (“locking back” the knee when standing)
Leg alignment or foot posture that alters front-of-knee loading

Fat pad pain is often part of a wider patellofemoral problem, so it is important not to treat it in isolation without understanding how the kneecap and surrounding structures are behaving.

Symptoms of fat pad impingement and lateral conflict pain

Common symptoms include:

Sharp pain at the front or front outer side of the knee
Pinching pain when the knee is fully straight or slightly hyperextended
Discomfort when standing still with the knees locked back
Pain with stairs, downhill walking, squats or lunges
Tenderness if you press either side of the patellar tendon, just below the kneecap
Swelling or a feeling of fullness at the front of the knee

Symptoms often flare with increased activity, long days on your feet, or exercises that push into end-range extension or deep flexion without good control.

How is fat pad impingement diagnosed?

Accurate diagnosis starts with a detailed assessment. In Bath and Bristol, Mr Abram focuses on confirming that the fat pad is truly the pain source and identifying why it is being overloaded.

Clinical assessment

History: onset, specific activities that worsen pain, previous injury or surgery, sport and work demands
Examination: tenderness around the fat pad, pain with extension, patellofemoral tracking, limb alignment, hip and foot mechanics

Imaging

X-rays: to assess bone alignment, kneecap position and any arthritis
MRI scan: can show fat pad inflammation, scarring, oedema, and associated issues such as cartilage damage or patellofemoral problems

The aim is to confirm that fat pad impingement is present and to check for other causes of front-of-knee pain, such as patellofemoral cartilage injury, plica, or tendon problems.

Non-surgical treatment (first-line care)

Most patients with fat pad impingement or lateral conflict pain improve with targeted non-surgical treatment. The key is to reduce irritation while improving strength, control and movement patterns.

Activity modification

Reduce or temporarily avoid activities that sharply flare symptoms (deep lunges, repeated jumping, hyperextension)
Avoid standing with the knees “locked back” in hyperextension
Adjust training volume and surface to allow the knee to settle

Specialist physiotherapy

Physiotherapy is central to successful treatment. A tailored programme typically includes:

Load management and graded return to activity
Hip and glute strength to improve leg alignment and control
Quadriceps and hamstring flexibility and conditioning without provoking impingement
Balance and 'proprioception' optimising control of the whole muscular 'chain'
Movement retraining (landing, squatting, stair technique)

Bracing, taping and orthotics

Taping or bracing to help offload the fat pad or improve kneecap tracking
Footwear and orthotics to modify load, where relevant

Injections

In some cases, a carefully placed injection can help reduce inflammation and pain, making physiotherapy easier. Options may include:

Image-guided local anaesthetic and steroid around the fat pad in selected cases
Other injection options where there is coexisting osteoarthritis or synovitis

Injections are used judiciously and always as part of a broader plan, not as a stand-alone fix.

When is surgery considered for fat pad impingement?

Surgery is reserved for patients whose symptoms remain troublesome despite well-managed non-surgical care, and where imaging and examination clearly support fat pad impingement or lateral conflict as the main pain driver.

Tibial Tubercle Osteotomy (TTO) for Fat Pad Impingement

In a small number of cases, fat pad impingement and lateral conflict pain are driven by underlying patellofemoral malalignment or patella alta (a high-riding kneecap). If the kneecap sits too high or tracks too far laterally, the fat pad and surrounding structures can be repeatedly pinched, and symptoms may persist despite excellent physiotherapy and injections.

Tibial tubercle osteotomy (TTO) is a realignment procedure that repositions the bony attachment of the patellar tendon on the shin bone. By shifting the tibial tubercle, the surgeon can:

Improve kneecap tracking within the groove at the front of the femur
Reduce lateral conflict where the outer fat pad and soft tissues are being pinched
Address patella alta in selected cases by lowering the kneecap to a more normal position
Redistribute patellofemoral load away from overloaded areas

TTO is not a first-line treatment for fat pad impingement. It is considered only when:

Comprehensive non-surgical treatment has been followed and symptoms remain limiting
Imaging and assessment show clear patellofemoral malalignment or patella alta contributing to the problem
There is a clear biomechanical rationale that realignment will reduce fat pad conflict and long-term overload

The operation is usually combined with a structured rehabilitation programme focused on controlling swelling, restoring movement and building strong, well-controlled patellofemoral mechanics. Where appropriate, TTO may be performed alongside other patellofemoral procedures (such as MPFL reconstruction or cartilage surgery) as part of a wider plan to address front-of-knee pain and instability.

Fat pad pain within patellofemoral problems

Fat pad impingement frequently coexists with other patellofemoral conditions, such as:

Patellofemoral pain
Kneecap maltracking or tilt
Patellar instability or dislocation
Patellofemoral cartilage damage or arthritis

For this reason, it is often managed alongside wider patellofemoral assessment and treatment, which may include physiotherapy, taping, bracing, injections, and in selected cases kneecap stabilisation or osteotomy procedures.

Recovery and outlook

With accurate diagnosis and a structured plan, many patients experience substantial improvement without surgery. Recovery usually involves:

Settling inflammation and reducing mechanical irritation
Improving lower-limb strength, control and movement patterns
Gradually restoring walking, sport and daily activities without sharp “pinching” pain

Where surgery is needed, most patients can expect a period of protected rehabilitation, progressive strengthening, and a structured return to sport or higher-level activity guided by their surgeon and physiotherapist.

Frequently asked questions

Is fat pad impingement the same as patellofemoral pain?

No, but they often overlap. Patellofemoral pain refers more broadly to pain from the kneecap and its joint surfaces. Fat pad impingement is a specific source of pain beneath or around the patellar tendon. Many patients have a combination of both.

Can fat pad impingement heal without surgery?

Yes. Many cases settle with targeted physiotherapy, load management, taping/bracing and, if needed, carefully selected injections. Surgery is reserved for persistent cases where symptoms remain limiting despite good non-surgical care.

Why does my knee hurt most when it is fully straight?

Complete extension or hyperextension can pinch the inflamed fat pad between the bones, triggering sharp pain. Avoiding prolonged “locked back” standing and adjusting movement patterns is often part of treatment.

Can I continue running with fat pad impingement?

Often you will need to modify or temporarily reduce running while the knee settles and strength/control improve. A phased return-to-run programme is usually planned with your physiotherapist and surgeon once symptoms are better controlled.

Can I be assessed in Bath or Bristol?

Yes. Mr Simon Abram offers specialist assessment of fat pad impingement, lateral conflict pain and related patellofemoral problems in Bath and Bristol, with a personalised plan that may include physiotherapy, targeted injections and, where appropriate, keyhole surgery.